I did do that but for some reason I lost my connection and when i tried it again it was telling me there was a problem.When you find something you want to buy, instead of clicking the button "Buy MP3 song with 1-click" look two buttons down to the $ symbol, it'll say "redeem a gift card or promotion code & view balance" and click on that link. Where it says "Enter new code" enter the code GET3MP3S & hit apply. Sorry, I though it was simple to figure out, I should have included this in the original post!
I had a similar issue the last time they did this, and it didn't take the $3 off. When I called Amazon to get it fixed, they fixed it and refunded the money that I spent AND gave me the credit again, so if you have problems call them, their customer service is great!I did do that but for some reason I lost my connection and when i tried it again it was telling me there was a problem.
I got it to work! Thanks OP