This is the basic hookup that goes inside your locomotive. The receiver board connects to the DCC amp using a standard servo type cable, this can be up to a foot long or so depending on your installation requirements. You will also need a ‘buck converter’ or similar device to provide a stable 5v DC source to power the logic. Once you have power for the logic, the hookup to the DCC decoder is done with the DCC amp. Two wires bring in the battery voltage, then two wires are hooked up to the DCC decoder track inputs.
Here is a pic of the DCC output of the receiver plugged into the DCC Amplifier Board.