What I did was put together a binder of printouts of examples from the user guide (electronic) as well as examples I found on the RAI website.
I went through all of these and sort of taught myself the mechanics of STAAD. I have some experience with FEM, so I knew what kinds of things STAAD requires for input, but the probram's front end is daunting, with a steep learning curve.
After I got comfortable enough with the program, I started playing around with examples and problems from my structures textbooks (Hibbler's Strutural Analysis, for example).
Give that a try.