Essentially you are using your own github account to do that. Write your code, commit it to github, and then share it with the rest of the world. Github has extensive help pages on their site. A good beginner’s guide is here: http://product.hubspot.com/blog/git-and-github-tutorial-for-beginners
I would recommend you start there and when you get stuck (or if you get stuck), let us know where/how, and we can try to help resolve the issue then.