Q: Where do I click to download/pay for a song to be added to my Nano? All is see are: add to wish list, recommend to facebook, etc.?

I need help in downloading songs from itunes onto my son's Nano before Xmas. I'm selecting songs I like but only see a button that asks: Gift to someone, Add to Wishlist, etc.  Where am I to look for the final button to click that will download each song.?