I found instructions on how to create ringtones via iTunes, but found an easier way using GarageBand.
These instructions, BTW, only work on a Mac.
I’m not going to include the nitty-gritty details, but all you have to do is:
1. Open GarageBand (4.11) and iTunes (7.5 and up).
2. Drag-and-drop the song you want to turn into a ringtone.
3. Turn on “Cycle” and set the start end end times (usually 30 seconds).
4. Click on Share | Send Ringtone to iTunes.
5. You simply need to sync the Ringtones with your iPhone and that’s it.
Enjoy and choose an awesome ringtone, please.