I downloaded a ringtown to my phone.
I don't remember how to find it.
I don't know how to make it my primary ringtone.
open phone, touch menu button (second from left) choose settings, then sound & display, lastly choose Phone ringtone. The one you down loaded should be there. You can download ringdroid from the market, cool app that allows you to use a song or something and cut it up where you like it for a ringer.