Once you've created and are happy with your release, simply click on the green "Publish Now" button in the Settings box to the right of screen.

Your release is now published!

Go share it with the world, and pop the champagne 🎉

NB publishing a release does not automatically send it to your subscribers, to do that you'll need to hit the blue "Email to Subscribers" button that will appear in a new "Share This Release" section once you've published the release

This allows you to pick and choose which releases you announce, and which you add to your list without fanfare.