Is there a program that would let me make my own music?

My niece uses this program to record her original compositions. She plays guitar and sings.
http://www.apple.com/ilife/garageband/

Fruity Loops is very sexy.. but costs money.

Audio Tool is cool but relies on you already having some sound samples for the most part. It is, however, a free online app.

If you use a PC and want to be able to do serious Music COmposition, print out scores and parts, etc, Cakewalk may be worth its modest price for you.

I’ve played with both Fruity Loops and Mixcraft 5. Both seem to be what you’re looking for.