On the right hand side of the scren, at the top, there is like four tabs (please forgive me if I am wrong, but I haven't got it installed at the moment), there is the one you are currently on, something like "shapes", "materials" and something else. You are after the "shapes" tab, there you can select the shapes you made, for ease of use, you may wish to rename the shapes, instead of box1 for example you could call it handle.
