cannot setup the facebook app

The documentation says setting up the facebook and twitter apps is easy. Not true!

Can someone who has successfully done this provide a step by step instruction as to how you did it?

The documentation provided is not accurate.

This is for a brand new wordpress blog, comments plus is the first plugin I installed.

It says:

You must make a Facebook Application to start using Comments Plus.

Before we begin, you need to create a Facebook Application.

To do so, follow these steps:

Create your application
Look for Site URL field in the Website tab and enter your site URL in this field:

WHERE is this Site URL field? In facebook, it asks you to create an App Display Name and App Display Space. The documentation makes no mention of this or what to put there. It also asks for App Domain, and I don't know what to put there either. I don't have a field for Site URL. Instead, it is asking me to install Cloud Services, from which I can pick a site URL from one of the many cloud services facebook deals with. I tried picking Heroku, but then it gets all the more confusing from there...Heroku sends me to a page where I have to go through a bunch of steps to get it working with...PHP, or Ruby, or countless other types of interfaces, I don't know which to pick, and the Comments Plus documentation doesn't tell me.

After this, go to the Facebook Application List page and select your newly created application
Copy the values from these fields: App ID/API key, and Application Secret, and enter them here.

I found those values and pasted them in, but the app isn't working. Facebook tells me "You have specified an App Domain but have not specified a Site URL or a Mobile Web URL must be derived from your Site URL or your Mobile Web URL."

Yes, the domain is

I'd be happy to provide the login/password information to anyone willing to assist, but I'd love to know what I'm doing wrong. I hope I'm making this more complicated than it needs to be! It would be a relief to know it's simpler than it seems.