Use iTunes to Convert Audio For Your iPhone Ringtone

Make sure you have iTunes on your computer first, as well as an MP3 or WAV of the song you need to convert. Import the audio or music file into iTunes on your PC/Mac, and convert the file to AAC. Rename the file extension to .m4r, followed by syncing the file to your iPhone. If you have GarageBand, there's a feature to save audio as a ringtone.