2 Answers

You have to download itunes first. I think if you hook up your ipod to your computer for the first time, it automatically downloads itunes to your computer.  If not  go to www.itunes.com and you should be able to download latest version for free.

Once that's set, you can download directly from itunes stores. Or if you download from other sites, download first to your computer and you have to manually bring it to your itunes.  From files menu, click on either 'add file to library' or 'add folder to library'.  Browse to where you have downloaded your music and click on the file or folder you want.  It should then bring the music to your library on your itunes.  When you're ready to download song to ipod, from file menu, click on 'sync  ipod'.  Good luck.