Do you want to be an open source contributor? If you're interested, please follow Aidan Feldman, one of the most well known hackers in NYC, to get familiar with Git!
Aidan Feldman is Education Hacker at GitHub by day, dancer by night. On the side, he organizes Hacker Hours, volunteers at CoderDojo, bikes, and teaches Advanced JavaScript at NYU. api.afeld.me.
In this workshop, Aidan covered the common Git workflow, including publishing a project on GitHub, and how to collaborate on an existing repository.
See source code here:
Here are a bunch of resources for learning Git/GitHub:
https://help.github.com/articles/what-are-other-good-resources-for-learning-git-and-github
In particular, you could also check out Try Git to review the basics:
https://try.github.io/levels/1/challenges/1
In addition, you are welcome to Hacker Hours!