With your cursor hovering in the 3D window press AKEY to deselect all elements. Vertices will turn pink. Now press BKEY; the cursor will change to a couple of orthogonal grey lines. Move the cursor above the top left corner of the cube, press and hold LMB, then drag the mouse down and to the right so that the grey box encompasses all the leftmost vertices. Now release the LMB. This sequence, which lets you select a group of vertices in a box
When I do this it does not select the vertices that are behind the front vertices. Am I doing something wrong?
if you are in shaded mode, then the box select only selects the vertices that you can see. either press [z] to go into wireframe mode, or, in the header, there is a box that you can deactivate to allow you to select vertices through your mesh. the buttons is a shaded box and is next to the vertex/edge/face mode buttons.
also, this is the developers forum. you should post questions at a user forum, like www.elysiun.com