Walkthrough Sync your Fork - rkerschbaumer/oom GitHub Wiki
You should regularly sync your own fork with the original repository (upstream repository) to stay up-to-date.
First, configure a remote for the original (upstream) repository. A remote is just another repository from which commits can be fetched into your own repository:
https://help.github.com/articles/configuring-a-remote-for-a-fork/
Now you can regularly fetch all new commits available in the upstream repository and merge them into your own repository: