It's very likely that you'll have to remove the stereo from the dash and manually eject the cd. Basically you will pry it carefully out of the transport mechanism. Usually they are open on the top, but if not, you'll probably still get it out one way or another if you *really* want that cd back.
You probably need a new stereo. They rarely jam like this just once. It'll probably eat another disc either immediately or in due time if you do get this one out.