CD code entry

I recently disconnected the battery on my ford freestar 2004. After connecting it back after several hours. I have a 6 cd player in dash original equipment. The radio works fine but there are 6 cds in the player and when I press the cd button I get a message that says "initiallizing" My thought is it is about a code that needs to be put in for anti theft. Where do I get the code and how do I put it in?