There are three ways to create a branch:
Once your branch is created, you can start writing! Changes will not be live until you merge your branch into a public version.
You can switch between branches at any time from the version picker in the top-left of the editor. Your draft on the current branch is saved automatically before you switch, so nothing is lost.
Branches are isolated from each other — edits made on one branch won't appear on another until they're merged. This makes it safe to draft major rewrites or experiment with structural changes without affecting your live docs.