One of the problems you will have when you go to learn how to sing is that most instructors will want you to learn one particular type of music. They may focus on one sing for weeks or even months, but by choosing to learn singing on cd, you can learn what you want when you want it, and at the pace you prefer.
Singing lessons on CD are a great way to learn how to sing and grow in confidence every time you open your mouth. They are also a lot cheaper than traditional lessons that you would take in person.