Currently Being ModeratedAug 19, 2012 12:25 AM (in response to tktschida)
You can't use iTunes to transfer song files from iPod to computer, except for songs you purchased from the iTunes Store (and you can also re-download purchases from the iTunes Store Purchased page). However, there are third-party methods and utilities that can transfer from iPod to computer. If you do a Google search on something like "ipod transfer," you should get some links.
Once the songs files are on your computer, you can add them to your iTunes library by dragging the song files (of the folder containing the files) to the iTunes window.