If you're new to the using of Git, I highly recommend Git Immersion. It's about 50 pages going though the basics of Git. I've been using git to get files for years, but never got into the minutia of things, since I never had changes to push back to the repository (end user, not developer). But since every job posting I've seen in the last 6 months has Git, or something similar in practice. as part of the desired skillset, I decided I needed to learn to do more than 'git pull'. So if you want to grok git, this is the place to do it.