When you select objects, you specify what type of object you want to select (lines, parts), and how you want to select it (point, rectangle). In addition, the <Shift> and <Ctrl> keys can be used to adjust the selection method (add, toggle, subtract).
You set the type of object to select under Selection Select. You can also find the same commands under Quick Access Toolbar
Select. You can also find the same commands under Quick Access Toolbar Select.
Select. 
Options available in all environments
 Select
Select Parts to select entire parts. You can also select parts in the browser (tree view).
Parts to select entire parts. You can also select parts in the browser (tree view).  Select
Select Surfaces to select surface entities. You can also select surface entries in the browser.
Surfaces to select surface entities. You can also select surface entries in the browser. Options available in FEA Editor environment
 Select
Select Edges to select edges. You can apply an edge force, boundary condition, or elastic, rigid, or displacement boundary element to edges you select.
Edges to select edges. You can apply an edge force, boundary condition, or elastic, rigid, or displacement boundary element to edges you select.  Select
Select Lines to select lines. Use when you change the layer attributes for lines in your model.
Lines to select lines. Use when you change the layer attributes for lines in your model.  Select
Select Construction Objects to select construction circles, arcs, lines, and vertices.
Construction Objects to select construction circles, arcs, lines, and vertices.  Select
Select Vertices to select vertices. Use to apply boundary conditions and forces to vertices.
Vertices to select vertices. Use to apply boundary conditions and forces to vertices. Options available in Results environment
 Select
Select Nodes to select nodes. Use to view the results at a specific node.
Nodes to select nodes. Use to view the results at a specific node.  Select
Select Elements to select elements. Use to view element statistics.
Elements to select elements. Use to view element statistics.  Select
Select Faces to select element faces. Use to view results on element faces such as the heat rate of a face.
Faces to select element faces. Use to view results on element faces such as the heat rate of a face.  Select
Select Beam Members to select beam members for code checking.
Beam Members to select beam members for code checking.  Select
Select Loads and Constraints to select FEA-type objects such as loads and boundary conditions. Use Results Inquire
Loads and Constraints to select FEA-type objects such as loads and boundary conditions. Use Results Inquire Inquire
Inquire Loads and Constraints to list properties for selected FEA-type objects.
Loads and Constraints to list properties for selected FEA-type objects. How you select objects is set from Selection Shape. You can also find the same commands under Quick Access Toolbar
Shape. You can also find the same commands under Quick Access Toolbar Select.
Select. 
Combination selection mode—click a single object or use a rectangle to select multiple objects:
This mode will suit the vast majority of selection tasks. Click to select the object at the cursor location. Alternatively, hold down the left mouse button, drag to draw a selection rectangle, and release the button. In the FEA Editor, objects fully enclosed within the rectangle will be selected. In the Results environment, objects that the rectangle intersects will also be selected.
 Shape
Shape Point or Rectangle.
Point or Rectangle. Use a rectangle to select multiple objects:
 Shape
Shape Rectangle.
Rectangle. Use a polygon to select multiple objects:
 Shape
Shape Polyline.
Polyline. Use a circle to select multiple objects:
 Shape
Shape Circle.
Circle. Use Reset To Point:
When active, Reset To Point resets the selection shape to Point or Rectangle after you perform a selection. The command functions as a toggle—click it to activate the option and click again to deactivate it. The option highlights when active.
If you typically use the Point or Rectangle selection shape, you may find it convenient to use Reset To Point. For example, when Reset To Point is active and you perform a Polyline selection, the selection shape reverts to Point or Rectangle once you close the polygon. If you want to make multiple selections with other shapes, such as Polyline or Circle, deactivate Reset To Point.
You can use four methods when you select objects with the selection shapes:
The following commands are similar to the selection methods but operate on the entire model:
 Select
Select None to unselect everything. You can also click the <Esc> key if the cursor is in a selection mode.
None to unselect everything. You can also click the <Esc> key if the cursor is in a selection mode.  Select
Select All  or <Ctrl><A> to select all objects of the current selection type and unselect other types of objects.
All  or <Ctrl><A> to select all objects of the current selection type and unselect other types of objects.  Select
Select Invert to unselect objects not in the current selection type and invert the items selected in the current selection type. For example, if part 1 and some other vertices were selected, the Invert command in part selection mode selects all parts except for part 1. While in vertices selection mode, the Invert command selects all vertices except the original ones.
Invert to unselect objects not in the current selection type and invert the items selected in the current selection type. For example, if part 1 and some other vertices were selected, the Invert command in part selection mode selects all parts except for part 1. While in vertices selection mode, the Invert command selects all vertices except the original ones. Use the filter to control the items you select.
 Filter
Filter Loads Constraints to filter the selection set for the appropriate FEA objects. In the Filter dialog, options are available based on the analysis type and selection method. The options you select in the filter determine which objects remain in the selection set.
Loads Constraints to filter the selection set for the appropriate FEA objects. In the Filter dialog, options are available based on the analysis type and selection method. The options you select in the filter determine which objects remain in the selection set.  Filter
Filter Line Length to select lines between the minimum and maximum filter lengths.
Line Length to select lines between the minimum and maximum filter lengths.  Filter
Filter All Parts/Surfaces or Selection
All Parts/Surfaces or Selection Filter
Filter No Parts/Surfaces to change the filter status for all parts and surfaces. You can also right-click parts and surfaces in the tree view and select or clear Enable Filter. The filter icon
No Parts/Surfaces to change the filter status for all parts and surfaces. You can also right-click parts and surfaces in the tree view and select or clear Enable Filter. The filter icon  appears on appropriate items when the filter is on.
 appears on appropriate items when the filter is on. Select Neighbors
You have two neighbor selection modes available in the FEA Editor environment. With Selection Mode
 Mode Select Neighbors active, the vertex or line you select and all vertices or lines immediately next to it are selected, respectively. For example, if you select a line in the middle of a square grid, all lines in contact with the line are also selected:
Select Neighbors active, the vertex or line you select and all vertices or lines immediately next to it are selected, respectively. For example, if you select a line in the middle of a square grid, all lines in contact with the line are also selected: 

Use Selection Expand
Expand Neighbors after you select one or more vertices. The command adds all the vertices or lines, immediately near the current selections, to the current selection set of vertices or lines, respectively. Use this command several times to quickly select vertices or lines in a specific area of a model.
Neighbors after you select one or more vertices. The command adds all the vertices or lines, immediately near the current selections, to the current selection set of vertices or lines, respectively. Use this command several times to quickly select vertices or lines in a specific area of a model. 
Select Chain Border
In line select mode, use Selection Expand
Expand Chain Border to select a chain of lines beginning and ending with the line you select. The chain also ends when it runs into a previously selected line. This command is useful when you select the perimeter of a part or hole.
Chain Border to select a chain of lines beginning and ending with the line you select. The chain also ends when it runs into a previously selected line. This command is useful when you select the perimeter of a part or hole. 
The Selection Expand
Expand Chain Border
Chain Border Largest Chain setting determines which chain of lines you select. If the selection is not appropriate, try toggling the Largest Chain option. In general, to select the outside perimeter, use this option. To select an internal perimeter with sharp corners, do not use this option.
Largest Chain setting determines which chain of lines you select. If the selection is not appropriate, try toggling the Largest Chain option. In general, to select the outside perimeter, use this option. To select an internal perimeter with sharp corners, do not use this option. 
You can right-click in the display area and click  Subentities to change the type of objects selected. You can also click Selection Subentities. For example, if you select a part, but want to apply pressures to all the surfaces on the part, right-click and click Subentities
Subentities. For example, if you select a part, but want to apply pressures to all the surfaces on the part, right-click and click Subentities Surfaces. All surfaces on the part are selected.
Surfaces. All surfaces on the part are selected. 
The following list displays the geometry object hierarchy. You can change the selection set object type to any subentity of the select parent. For example, if your selection set is Elements, you can down-select to Faces, but you cannot up-select to Surfaces.
 Select setting to the chosen subentity type.
Select setting to the chosen subentity type.