Hi Chuck, I'm entirely sure if this is what you mean, but if you want to have a box on one side, you can create it by this method.

Start by running the Draw solid / Box command, located here:



Place the first 2 points something like this:



And the 3rd point for the height something like this:



Then in this case I went to the Front view and dragged the box downwards a bit, to result in this:



Now you can fuse those 2 pieces together by selecting them both and running Construct / Boolean / Union.

- Michael