How do I add to a previous support post?

I submitted a question earlier this morning and Jack Kitterhing responded. I want to take him up on the offer to help me with developing a FB app so I can use Facebook Ultimate.

Here is the link to the original post.
https://premium.wpmudev.org/forums/topic/autopost-to-facebook-how-to-achieve-simply#post-508828

Here are my follow-up issues:

I'm following the video tutorial for creating an app. However, when I enter the App Domain of "uuama.org" I get this error message:
"You have specified an App Domain but have not specified a valid integration URL. uuama.org must be derived from one of : Site URL, Mobile Site URL, Canvas URL, ... etc."
Where do I go from here?