The official public repository is hosted on Github. To get the code, install git and run:
git clone https://github.com/xinu-os/xinu
This will generate the directory
xinu/ containing a local copy of the repository. Note that this is a standalone repository that can be used without Internet access to the Github repository. This constitutes a difference from Subversion, which is more centralized.
Git is documented extensively in many locations, for example in the "Pro Git" book. But briefly, a very basic workflow is to modify files, use
git add and
git commit or
git commit -a to commit the changes to the repository, then use
git push to push changes to a remote repository.
Branches in git are fast and easy to use, so please develop experimental features in their own branches. Code pushed to the "master" branch should not be broken.