Webdesigner Depot has posted a great Intro to Git for Web Designers. It walks through what version control is, why you should use it, the advantages of using Git, and then walks you through Git usage. It’s very thorough and does a great job.
The end of the article contains a ton of great resources, as well – from cheat sheets to walk-throughs.
It’s also a great compliment to ENTP’s similarly titled Git for Designers.