Once you've tested your course, it's time to publish it! The course must be in draft mode in order for it to be published.
A course that's in draft can be published as follows:

Your course will now be publicly accessible, or accessible by members of your organization if it is private.
Future changes to your course repository's master branch will automatically update the course, while future work on a new branch or pull request will create a draft branch for you to test.
See Making changes for more information.