This is where I publish my source code. I maintain my code with Bazaar, which is a distributed revision control system.

To check out a branch, you can use:

bzr get http://code.jozilla.net/package-name

To get the URL of the branch, you could also copy the source link in the bar at the bottom right of the description of a branch.

Once you have a copy, new updates can be retrieved by using the command:

bzr pull

Or when you have already made your own changes:

bzr merge

For more information on how to use Bazaar, have a look at the documentation.