i do not have cs3, cs2, or cs1 illustrator. But i just purchased a new cs4 for my ibook g4, how can i install without previous serial numbers?

Hello...I'm still kind of fresh to the Apple world.  I did not know that you needed previous apps to add an old one.  In my pc days, you just cleared your drive.  Help!  I hope I didn't blow my money on an old laptop and new program!!!!