I'm trying put my credit card information for a game called big fish casino and its not letting me buy coins

What happens when you try to add your card and try to buy something, do you get any error messages ?

If you are getting a message to contact iTunes support then you can do so via this page and ask them why the message is appearing (these are user-to-user forums, we won't know why) : http://www.apple.com/support/itunes/contact/ - click on Contact iTunes Store Support on the right-hand side of the page

If it's a different problem ... ?