you need to download iTunes. (well, you don't
need to, but it will make thing easier).
Do you know where all your music is on your hard drive? there is probably a folder in your "My Documents" called "My Music", i would bet it is there.
Install iTunes, open it, and then click and drag your "My Music" folder (or whatever it is) into your iTunes. It will load the files into iTunes - it will pretty much be like using WMA, except now it's iTunes, ya dig? And if it asks you if you want to copy the files to an iTunes folder, you don't have to, because then you will have two copies of all of those music files, and that's gonna take up a whole lot of space.
Then, plug in your iPod. You will see it on the left sidebar of iTunes. It will automatically "synch" all of your music onto your iPod.
let me know if you have any questions.
