Is it possible to add a role on users after they register to my dotnetnuke site through facebook?
I'm using the out of the box version of the facebook login control located at DesktopModules\AuthenticationServices\Facebook\Login.ascx
and after the login procedure is done I want to add a role to the created user.
Is this possible through settings? If not, is there a way to determine in code if the user is registered through facebook?
I don't believe this is possible in the standard FB provider for DNN. You likely would need to do this via the database, I would recommend looking at a user that you know was added through FB and see if you can see any differences in their profile from a regular user (likely in their username) and see if you can create a SQL trigger that handles that role addition.