Do you use OneNote online? How to make a new notebook?

I’m talking about the pared down OneNote that you get access to when you sign up for an email account or onedrive.

I know I have created a new notebook before, because I have two of them. But for some reason, the method for creating a new notebook is completely escaping me. I can get the page that lets me select which of the two notebooks I want to go into, but neither from that page nor from within either notebook do I see any option for creating a new one.

Googling seems to turn up only a claim (at microsoft’s help sites) that there should be a giant “create” button somewhere but I don’t see one.