Firefox Developer Tools
NOTE: This is the documentation for working on the Developer Tools. If you are looking for help with using the tools, please check out the end user documentation instead.
First of all, thank you for making it this far!
Developer Tools is a complex web application, and learning the code base will take some time, even if you're a very experienced contributor to other projects.
Likewise, getting and building the code locally, sending contributions for review, and other essential tasks can take a bit longer and be a bit different from what you're used to seeing.
But there are good news: most of the initial, lengthy tasks don't need to be repeated once your computer is set up. And there's a huge infrastructure in place (both technical and people) to ensure that many commits can land into the Firefox repository with the peace of mind that the code is peer reviewed, can be built and passes the tests, in multiple configurations and operating systems.
So don't be afraid of committing errors: you will. This is what happens to us all the time.
It's a big system, and no one knows absolutely everything. What we do know is that we are not going to break Firefox. If we do something wrong, the system will let us know before we mess things up for real. Users won't ever notice, and you will learn a new thing.