Are there any way to do this? I see referrer hidden field in registration form. I don't know how to use it.
How do i know which country the user registered from, and can i add a country field durring th registration?
You can attempt to locate them based on their IP, which is stored in the db, but there's no guarantee it will be accurate.
You can add a field to registration using a plugin, no way to do it in core.