Open iTunes on the pc. Plug ipod in. Click on your device in the column on the left. Check 'back up to this computer'. Enjoy.
Next click on icloud and sync you backups there.
Lastly, you can always transfer your songs to a cloud service like iPod to PC transfer, assuming you have less than 5gb of songs. Then you can access your songs anywhere, on any device, at any time.
Step1: Download the Pod to PC transfer.
Step2: Change your sync mode to Manually-Sync before connect to your iTunes.
Step3: Run iPhone to PC transfer and transfer all your music you want to add to iTunes to your computer first. This tool will not erase anything on your iPhone or iTunes.
Step4: Add music from your computer to iTunes.
That nice software works with Windows only and costs a bit more than 20€, but the OP didn't state any OS preference anyway.