What's a good way to save my own compositions

Hello,
What's a good way to save my own compositions? Leave them in Garage Band, change them to MP3, burn them to a CD as is? There is so much to learn. I find I'm a pretty good composer with my Garage Band, my Macs and MAudio Keystation. I like modern classical music like Phillip Glass and Morton Subotnick. Where can I go to learn and save my stuff? Is saving them in ITunes tantamount to loosing them forever? Can I retrieve the music and return it to Garage Band for editiong? classical duck quack quack