Using "Photos" Version 1.0 (209.52.0) that just got "put" on my computer at last update. Here's what my share menu looks like:
Here's the support page where I looked for help.
Goal: expose photo album via a URL I can copy/paste to people.
Share it with the person - then once the album is created, in Photos, there will be an icon with a head in a circle. This is the settings pane for the shared photo album.
Not obvious, but it works.