The Fray – You Found Me

How do you put music on your iPod Nano from your Computer?
I just got an iPod nano and I have some songs from my old MP3 that I want to put on it. The setup isn't the same as my old MP3, where you could just click and drag music files into folders marked 'Music' or whatever. Do you have to have iTunes to put music on your iPod nano? If so is it possible to put already existing music files in my computer in there without having to go re-buy them?

The Fray You Found Me (c) (C) 2008 SONY BMG MUSIC ENTERTAINMENT … The Fray You Found Me Rock Music Video