The #coding channel is where you can meet developers working with Mozilla's codebase. We've got a lot of code, and nobody knows it all, so if you feel stuck, don't be afraid to ask for some guidance!
(If you don't have an IRC client installed, try Mibbit, a web chat client, it works without installing software)
We have some documentation to get you started. Check out https://developer.mozilla.org/En/Developer_Guide .
Sometimes it’s quicker just to ask someone.