You can make custom ringtones from files in your iTunes library without using any additional software. Follow these instructions:
These instructions were tested using iTunes 9.0.2 on Mac OS X 10.5.8 and may vary depending on the version of iTunes and operating system you are running on your computer.
1. Choose the song you'd like to use for your custom ringtone.
2. Make a note of the beginning and ending time (this can be no longer than 40 seconds).
3. Right-click on the song you want to use for your ringtone and select Get Info.
4. Click the Options tab.
