Question

I am a newbie with facebook applications.

Ok. I should create a fanpage. This should connect to my Rails application.

So If user is a fan I should show “fan page 1”, else i should show “fan page 2”.

How could ask permissions on facebook fan page?

Thanks in advance and excuse if you don´t understand my question.

Answer 1

You have a couple of options.
The easy one is to use on of the FB apps like Static HTML Tab that lets you put in some HTML (usually an iframe) for the fan, and another for the non fan. Here ar some of the apps:
Static HTML App
http://www.facebook.com/apps/application.php?id=190322544333196

Or a round up (some paid)
http://www.socialmediaexaminer.com/top-10-facebook-apps-for-building-custom-pages-tabs/

Then your second option is to develop it your self. It is not that hard.
In your App Settings there is a field fot your TAB URL. Point that to a file you would like to use as a tab somewhere in the directory of your app. in PHP you_domain.com/app/tab.php

When Facebook loads that URL in a tab it will pass it a signed request that contains basic information about the user Liker or not, Locale etc.
You can extract that data and depending on that information show one piece of content or the other.
Here is a post on how toparse the signed request with rails:
http://qugstart.com/blog/ruby-and-rails/facebook-base64-url-decode-for-signed_request/