I as well would recommend tutorials...or better yet, I'd recommend SolidWorks
Seriously though, as great as CAD tools can be, by the time you learn to use the program, you won't have much time to build. I would work off of pencil sketches and designs for this year, and focus on learning a CAD program for next year. Great robots can be built without CAD, so view it as a nice to have down the road, but not a necessary for this year.