Do you see the iPod icon when you attach it to the computer?
iPod not recognized in 'My Computer' and in iTunes for Windows and Apple - iTunes - Tutorials - Learn about all things iTunes. perhaps.
You can sync the ipod to your iTunes, either automatically or manually. 'To sync manually, select the exact items you want to add or remove and drag them to and from your iPhone or iPod.' Apple - iTunes - Tutorials - Learn about all things iTunes.

Manual Updating of iPod (best watched with VLC player) and How to transfer music to my iPod (& iTunes) page 2