You can easily turn any song on your computer into a ringtone for your iPhone! You can use any song you have and turn it into a ringtone.

All you need to do is: 

1. Find the song you want to make the ringtone out of. 

2. Then you'll need to create a 30 second clip. You can use music editing programs like Garage Band.

3. Save your edited file as a .AAC file. 

4. Then you'll need to rename the file extension of your edited song from .AAC to .M4R. 

5. Now drag and drop the file into iTunes. 

6. Plug your iPhone in, then from the ringtones section in iTunes, drag the new ringtone to your iPhone. The new file should then sync. You can find and change ringtones on your iPhone from Settings > Sounds > Ringtone.