I wanted ringtones and didn't want to pay to download a song I might already have, so I searched for a while to find something that worked. Here's what worked.
1) Open iTunes.
2) Select File\Add File to Library to add .mp3 clip (30 sec. or less).
3) Right click file, select Create AAC version
4) Right click on the file created and select Show in Windows Explorer
5) In the window that appears, change the file extension to .m4r. Click yes to confirmation.
6) After extension has been changed, double click the file. It will appear under ringtones.











