In the No Film School newsletter -- which you should subscribe to, if you're not already, because it includes exclusive content not contained on this site -- I recommend beginning screenwriters check out the free screenwriting software Celtx. You won't find many pros using it (with Final Draft being the industry standard), but you can't beat it for the price. Now, thanks to FilmmakerIQ there's also a huge compilation of training resources for the screenwriting program.
Compiling 110 tutorials, the FilmmakerIQ guys have created the definitive resource for users of Celtx (click on the image to go to their page):
Also, iOS users might be interested in the iPad version of Celtx:
Link: 110 Celtx Tutorials