Hi Alan, welcome to the thread.
I am definitely not an expert, but among all of here should be enough help to get you started. First off, the help files (at least in my 2.2 version) are fantastic as to getting you started. The CAD program could use a little refinement, but for the most part is pretty easy to pick up.
Did you have any specific questions? My advice would be to start with one of their default rectangle rooms and just play around in the CAD editor. Get a feel for how to drag things around, resize things, add textures, etc. I understand it can get a bit confusing (especially since some options are available on one tab and not another even though they are similar).
Definitely get the patches, though. It fixes a very annoying bug regarding loading speakers. Sometimes mine would crash altogether (with any changes I had made).