How do I get to the downloads button on the itunes store homepage?

i bought a song but its not on my purchased list and i went back to see if it lets me buy it again and It says that the song has already been purchased and to go to the itunes store menu and click on downloads if i have any problems, but i cant find it. Where is it?|||If it already downloaded it should be in your Library when it's complete. Or you can go under iTunes Store (or something) in the left-hand column and look for "In progress" or "Downloading."