Hey, Jod77.
I see that you need to add your music to iTunes in order to sync it with your iPod nano, and I'm glad to help.
Redownload apps, music, movies, TV shows, and books from the App Store, iTunes Store, and Apple Books -- If you purchased songs from iTunes, you can redownload them again.
Import media from a computer to iTunes on PC -- This article explains how to add music already on your computer to iTunes for Windows.
Import songs from CDs into iTunes on PC -- If your previous iTunes Library contained music you imported from CDs you own, you may need to import them again if they're not located on your current computer.
Sync your iPhone, iPad, or iPod using iTunes on your computer -- Once the music is located in your iTunes Library, sync them to your iPod nano.
Take care.