Git is a version control system that works with 4 work areas, 3 of which are locations: Working , Staging , and Local in>. When you create the project it is initially in the Working area. When you modify data and add it to commit, they go to the Staging area. When you finish the work and commit, they go to the Local area, which is your still local repository. For everything to be sent to the Remote area, you need to use the git push command. That's what's missing so you can see your changes on GitHub.
For a better understanding of Git, I recommend this site pretty cool with a very interactive way of learning.