Since this is FREE and not through the Apple store, here's what you need to do:
1) Download this mp4r file to your computer or Mac. 2) Then, plug your iPhone into iTunes. 3) Click the iPhone icon in iTunes to open your iPhone iTunes menu (upper left corner of window, under the volume slider). 4) Now that you've opened your iPhone menu, on the left-side column, under "On My Device", click "Tones"- this will open your custom ringtone menu. 5) Drag and drop your downloaded ringtone from the "Downloads" folder into your "Tones" folder. 6) Sync your iPhone. 7) Click "Settings" on your iPhone. 8) Click "Sounds and Haptics". 9) Click "Ringtone", "Text Tone", or whatever you want to customize, then click this file name and you should be good to go!