You can select a song as your ringtone by loading the audio file onto your SD memory card. Play the song and choose Menu – Set as Ringtone. Alternatively select the apps tab from the Home screen and choose Settings – Sound & Display – Phone Ringtone and then choose the one you want.
You can also set specific ringtones for specific contacts by selecting a contact from your address book and pressing Menu – Options and then choose the ringtone you want from the list.