Extrude is a way to create 3d shapes from 2d shapes. The method shown here creates a cross section in an extrude node.
For information about the alternative method without using the extrudeNode see here. This method may be better if you want to do collision detection.
Start the program (see here for deails of how to load the program)
Insert a TransformGoup node. To do this click on to show the 'insert view', then drag a transfornGroupBean from the insert view to the tree view: