['Step One: Get iTunes. You almost never have to use iTunes with a modern iPhone, but adding your own custom ringtones still requires it. ... ', 'Step Two: Choose a Sound File. ... ', 'Step Three: Convert the MP3 to AAC. ... ', 'Step Four: Rename Your AAC File. ... ', 'Step Five: Add the Ringtone File to Your Phone. ... ', 'Step Six: Choose the Ringtone.']