You have to add a People Column to the Board in the top right corner, in which you can assign someone.
The private beta is refering to the versions before v0.1, when there wasn't a publicly hosted version.
Thanks but I have no idea how to do that, maybe I'm not even in the "board view" for starter.
Ok, found it, the small + icon. I would suggest to make it more obvious that this icon hides all the nice stuff
The onboarding is something I need to work on! I plan on having a basic example of some board right after you sign up.