Box Tool

Ribbon menu Bodeis Tab Solids container Box Tool
or
(Classic) Build Bodies/Geometry Box Tool
Creates a three-dimensional solid block.
You draw the box’s length and width in the plane of the screen or the working grid, if it is turned on. The Box tool creates a solid box with a depth that is twice that of the shortest dimension of the box (d = 2 * min(l,h)). You can also specify the length, height, or depth of the box before you draw it.
The box dimensions are in screen coordinates with the height up, length to the left, and depth out of the screen or grid:
Learn about Creating a Box.
 
For the option:
Do the following:
New Part/Add to Part/On Ground
Select either:
New Part - Creates a new part.
Add to Part - Adds the box to another part in your model.
On Ground - Adds the box to ground.
Tip: Add geometry to ground if the geometry does not move or influence the simulation of your model. For example, if you are simulating a car driving around a race track, the geometry that defines the race track can be added to ground.
Length
Enter the length of the box, if desired.
Height
Enter the height of the box, if desired.
Depth
Enter the depth of the box. If you do not specify a depth, Adams View creates a solid box with a depth that is twice that of the shortest dimension of the box (d = 2 * min(l,h)).
Note:  
One hotpoint appears after you draw the box. It lets you modify the length, height, and depth of the box. For more information on modifying geometry using hotpoints, see Using Hotpoints to Graphically Modify Geometry