So you've been working on your own code for a while now but have been hearing about Github and how it makes it simple to contribute to other projects too. Maybe you haven't found the time to get into git and Github yet. Well, this new post (a reprinted article from php|architect) to Lorna Mitchell's blog will tell you all you need to know.
Often I find absolutely competent programmers, who aren't involved in open source, either because they don't know how to approach a project, or because they just aren't sure how the process even works. In this article we'll look at one example, the conference feedback site joind.in, and how you can use GitHub to start contributing code to this project. Since so many projects are hosted on github, this will help you get started with other projects, too.
She covers all you'll need to know to get in and get going with Github - forking a current repo (she uses Joind.in as an example), cloning your fork, making updates and submitting them as a pull request back to the main project. There's also some things about general git topics like branching, merging from the upstream source and using "git log" to view the changes.