I keep mentioning this git book thing, but forgetting to link it.
The git book can be found at http://www.git-scm.com/book/en/v2
It's a bit hardcore, but it's an amazing reference and a good way to
learn the system if you have a few hours to burn. Chapters 1-3 are going
to be the most fruitful, but the rest of it is very good background
knowledge to have.
--
Mason Fabel