Once you add a Facebook fan page type to your app, you need to access your app's dashboard. Then go to Application Settings, there you need to fill in the Facebook App API Key and the Facebook App Secret.

As soon as your app is approved and published on AppStore, you need to go to your app's dashboard again and access AppStore Proprieties link. Copy and paste the link to your published app at AppStore to the "Share link" input field and then save the changes.