I'm writing a book, Dropbox for Dummies, that's designed to teach a new user the basics of Dropbox, and let them get the hang of navigating around, using the client and web interface, or even just navigating and using the forums. It's a long way from finished, but I'm currently 34 useful pages in, so if you would like to grab a preview copy as-is right now, you can get one for 0.0015BTC here.