sterlingrewards.co.cc - Add country field to sign-up

We would like a country field on our sign up field on our site so we can later use this for ad targeting. We need a simple drop down box with a list of countries in that allows the user to select there nation and then add that to information in our database. This information should be visable in the members area of the admin panel. Our site is [login to view URL] To have a look at our offers page you have to 1)sign up 2)log-in 3)click on earnings area 4)click paid to sign up