This is completed installation. Notice the front truck leads, the rear truck leads and the track power pick up leads from the decoder are are connected together on the circuit board at the cab end of the board.  The orange and gray motor leads are soldered to the right of the point where the traces are cut. The headlight is connected by soldering the blue and white wires to the front of the board, to the right of where the traces are cut as shown.  Traces cut here.