1. [[Bugzilla:Communicate|Get in communication with the Bugzilla developers]], and tell us what you want to do. This makes it easy for us to tell you "Oh, we're already working on that, you can help!" or "Oh, the best way to do that would be..."
2. If a bug has already been filed for what you want to do, check its [Bugzilla:Priority_System|priority].
3. Write some code. Make sure that you follow the [http://www.bugzilla.org/docs/developer.html Developer's Guide]. If you're new, you don't have to read the whole thing. Just read the [http://www.bugzilla.org/docs/developer.html#general General Guidelines], the [http://www.bugzilla.org/docs/developer.html#perl-style Style] section, and any other part that you think applies to the code that you're writing.