Rebase your work onto latest upstream.
Indeed, that is the part that I don't quite understand how to do...
I've done the following:
1. Created a fork of mame under my own github account
2. Cloned the fork in my workstation
3. Created a pull request a few days ago to update fork mame upstream, which resulted in a merge commit in my fork
4. Updated workstation clone
5. Applied all my code changes, and committed to workstation master branch
6. pushed changes upstream to fork
So my current changes are based on my_fork/master. I don;t understand how to rebase onto the latest upstream, and even if I did how would that work within the context of my fork?
(Sorry if these are stupid questions....)