Found this here when I got my ring tone:
http://search.vzw.com/?do=viewdoc&id=28309&supportview=1&p=-1Saving a ring tone - HTC DROID Aria ADR6200
1. From the home screen, touch the applications tab (located in the lower-left).
2. Touch Messages.
3. Touch the appropriate message.
4. Touch and hold the message.
5. Touch Save audio.
(mine just had save) 6. Touch Home.
7. Touch the applications tab (located in the lower-left).
8. Touch Music.
9. Touch the Library key (located in the lower-left).
10. Navigate to the desired location, e.g. Unknown artist > Unknown album.
11. Touch the desired tone.
12. Touch Menu.
13. Touch Set as ringtone.
14. Select the desired option.
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Hope this helps you if you haven't figured it out already.