To create parent-child relationships between objects in your scene, you can use either the Schematic view in the Viewer window, or you can use the Scene browser.
In the Scene browser:
To add additional objects to the selection. Ctrl-click them, then drag the selection to the parent object.
In the Viewer window:
A dotted line joins a parent and its selected child objects, and the parent object is highlighted. The parent is connected to the selected children, and the objects are rearranged in a hierarchy.
For example, the following figure illustrates two cubes before and after parenting in the Schematic view.
A. Before parenting B. After parenting, Cube 1 is the child of Cube.