Hiya, I installed Ultimate FB on leef.inaandacht.nl made

Hiya,
I installed Ultimate FB on leef.inaandacht.nl made an app with the help of the YouTube movie.
All went OK, but I get this message in the app center:

You have specified an App Domain but have not specified a valid integration URL.
inaandacht.nl must be derived from one of: Site-URL, Mobile Site URL, Canvas-URL, Secure Canvas URL, Page Tab URL or Secure Page Tab URL.

What does this mean?

Thanks in advance and best regards,
Ronald