The key to managing the music on your iPod is mastering Apple's iTunes software. To transfer songs to your iPod, all you have to do is check them. The next time you connect your iPod, all the checked songs in your Library will be downloaded.
Open the iTunes software and click the Library icon in the Source pane.
Check those songs you want to download to your iPod.
NOTE
Automatic Transfer
The next time you connect your iPod, all the songs you selected are automatically transferred.