I wrote a “Get Started with Git” guide for A List Apart:
Version control: It isn’t just for coders anymore. If you’re a writer, editor, or a designer who works iteratively on the web and you want to reshuffle or combine pieces of your work quickly and efficiently, version control is for you, too. Al Shaw shows us how easy it is to install, set up, and work with Git—open-source, version control software that offers you much, much, more than just “undo.”
Read the whole thing at ALA.