If you want to create your own ringtone for your iPhone, you'll have to download iTunes and find the song you want to use. Once you've downloaded iTunes to your computer, you can select a portion of the song to make your ringtone. Try to limit the song to less than 30 seconds to avoid the ringtone being too long. It's possible to record any song you want to use as a ringtone, but you can't make it longer than 30 seconds.