On this page, free downloads are available for ringtones and sheet music from my favorite original instrumentals.
Ringtone download instructions for iPhone:
Download the .mp3 files from this website onto a computer and rename the suffix from .mp3 to .m4r.
Plug your iPhone into that computer, open iTunes, and drag the .m4r files into your iPhone's 'Tones' library on iTunes.
Now you should be able to select the ringtones you'd like in Settings>Sounds>Ringtone.
For other devices, the original .mp3 file should be sufficient!