How do I transfer my itunes account from a desktop pc to a laptop when all of the music in the itunes account was from CDs we previously owned and not purchased?

How do I transfer my itunes account from a desktop PC to a laptop when all of the music in itunes was downloaded from CDs we already own (not purchased from itunes). We have a nano that already contains all of the music that is on the desktop. I just need to get it onto the laptop.