Before you can publish your page, the Publisher role needs to have been assigned to your user account.
It is important that you first review the content from a visitor's perspective by previewing the page,
Once you are ready to publish the page, follow these steps:
Ensure that the subdomain is active (otherwise, your users will see page load errors).
Turn Edit Mode to Off at the top of the page to enter Preview mode.
Click Publish at the top of the screen:
You will be asked to confirm that you wish to publish the page. The previous live version will then be completely overwritten by the modified version and you will be unable to roll it back.
Once you have published your page, continue to Launch your Tracking URL.