Q: I just redeemed my gift card.  50.00 is now in my apple account...when I go to download a song it wants me to verify my billing info. How do I redeem the gift card and not having the price go on my credit card??

I took this straight from the help menu.

You need to set up an Apple ID for use with the iTunes Store before you can redeem anything in the iTunes Store. You don’t need to enter credit card information to redeem only the amount of a gift certificate or card.

Hide 

Use an iTunes allowance, gift certificate, or iTunes Gift Card

1.   If you aren’t already signed in to the iTunes Store, choose Store > Sign In, or click Sign In at the top of the iTunes Store window. 

1.   Below Quick Links, click Redeem, and follow the onscreen instructions.

The amount in your account appears to the left of your account name. When you click the Buy button to make purchases, the amount changes to show how much money remains in your account.

You can use a gift certificate only in the iTunes Store for the same country in which the certificate was purchased.