Click Architecture tabModel panelModel Group drop-down (Create Group).
The Create Group tool is also available here:
Structure tabModel panelModel Group drop-down
Annotate tabDetail panelDetail Group drop-down
In the Create Group dialog, enter a name for the group.
Select the type of group to create (model or detail), and click OK.
Revit enters group edit mode. The background color of the drawing area changes when you are in group edit mode.
If there are elements in the project view that you want to add to the group, click Edit Group panel (Add), and then select the elements.
If you want to add elements to the group that do not already exist in the project view, select an element creation tool from the appropriate tab and place the new element. When you add an element to a view in group edit mode, it is automatically added to the group.
Note: If you add a view-specific element to a model group (for example, a window tag), the view-specific element is placed in the project view and not in the model group.
When you are finished adding elements to the group, click Edit Group panel (Finish).