Gecko:Getting Started

The first step is to download and build Mozilla or Firefox: see https://developer.mozilla.org/en-US/docs/Mozilla/Developer_guide/Build_Instructions

See the information on hacking Mozilla for how to work with the Mozilla project and coding conventions.

If you get stuck at any point, send a question to a Mozilla newsgroup, or get onto IRC at irc.mozilla.org, channel #developers. Do not give up, there are people who want to help you.

If you're looking for a "first bug" to get started with, check out Gecko:First Bugs.