How do I publish a gallery?

A gallery is a private draft until you publish it; publishing puts it online at its link.

Open the gallery and press Publish… at the top. It opens Settings.
The line at the top says what's still missing, if anything. Once it says Draft, ready to publish, press Publish.
The gallery goes online and the Share tab opens, with its link ready to copy or send.

Why isn’t it working?

Publish is greyed out: The line beside it says why: Add photos first., Set the password in Access. or Give the gallery a name.