To publish a Subject, first make sure you're in edit mode (admin and self views will not give you the option to publish). Once Topics and Step content have been created, and Advanced Settings have been determined, click the "Unpublished" button to toggle it to "Published."
If you still have Topics in Draft (gray circle) or Pending Review (yellow circle) statuses, you'll be asked if you wish to "Publish as is" or "Finish all and Publish".
Publish As Is
Selecting Publish As Is will publish the Subject but assigned users will only see "Finished" Topics.
Finish All and Publish
Selecting Finish all and Publish will change all Topics with Draft or Pending Review statuses to to Finished, which will effectively deploy ALL Topics to assigned users.
When a Subject has been published, assigned users will receive an email notification that new content has been assigned.