Dodge interprit i changed my car battery and my cd player needs to be decoded but idk what it is?

You had the battery disconnected for a long enough period that the player thought it was being stolen, and shut down. To get it up and running again, just enter the correct code. If you bought it after market, it will be in the papers you were given when you paid for it. If it's factory, it will be on the card in the manual. In either case, read the procedure for entering the code, and enter it. It will again work.