Hi civeng80,
Inventor actually has some decent tools for doing some structural work, in that you can sketch a skeleton and then apply structural members to the sketch, but, I'm not sure I'd want to tackle an entire building with this. Architectural Desktop (AutoCAD Architecture) is probably best for this application. Autodesk says Revit is the "wave of the future" and the way it looks, it probably always be - meaning it hasn't taken off like Autodesk had hoped it would.
To answer your original question though, AutoCAD actually has some decent tutorials in their help files, start there, and see if fills the need, if you're a structural/archictectural guy, you probably won't need much more.
HTH
Todd