With git you should make all your changes in a local branch. Once your change is committed, you can delete this branch.
Create a local branch named "mywork" and make changes to it.
Commit your change locally (this doesn't commit your change to the SVN or Git server)
git commit -a
If you added new files, you should tell git so by running git add <files> before committing.
Upload your change for review
git cl upload
Send a try job
git cl try
See Contributing code for more detailed git instructions, including how to update your CL when you get review comments.
There's a short tutorial that might be helpful to try before your first change: C++ in Chromium 101.
Follow these instructions.