Okay, I know these tutorials aren't by me. They're by lazyfoo. But I've been seeing far too many people asking simple SDL or game mechanics questions that could easily be answered by looking through his tutorials, so I'm going to post the link here.
He does just about EVERYTHING you need to know about SDL, and quite a bit that is useful for game dev, including multiple types of collision detections and a ton of other stuff.
http://www.lazyfoo.net/SDL_tutorials/index.php

