Thanks for offering to help us build Mozilla's websites!
Please start Start by joining us in #webdev on IRC. http://mzl.la/irc_getting_started will help you get connected, and http://mzl.la/webdev_irc lists some more WebDev channels.
Next you want to register an account on bugzilla. Bugzilla can be daunting, so check out the "Bugzilla for humans" video at http://mzl.la/bugzilla_for_humans(15m video HIGHLY recommended).
Now look for a WebDev mentored bug in http://mzl.la/webdev_mentored_bugs and contact the mentor - over IRC, email, or comment on IRCthe bug. Finally, with your mentor, fork the github repository for the bug's website and you're ready to start coding!
===Potential Contributors===