I think Alibre do some online tutorials. Alibre is a 3D parametric package, but personally I wouldn’t ever go back to 2D CAD systems. I design everything (professional and hobby) in 3D. The 3D packages normally automatically generate 2D drawings. You usually have to place dimensions and notes to suit. The dimensions are sized automatically, all you do is click on the two features you want to dimension. However, everything is associative; change the 3D model and the next time you open the 2D drawing the dimensions update automatically.
Alibre used to do a free low-end version, but they seem to have stopped this. They now offer a low-end package for $99.
Regards,
Andrew