On the Rx13 boards you DON'T connect the white wire from the switch to the smaller board. This can be removed. The only soldering you do on the smaller of the two boards is connect the aerial. Link the two board with the umbilical lead.
On the power switch, you connect the red wire to the main board and the black wire direct to the black wire for the main battery connector.
If you want to make the mg flash you connect the thin red and black wires from the LED to the turret connection socket (red to the empty solder point alongside the existing white wire, leave a space then the black to the empty outermost solder point
You've already soldered the motor wires onto the board, so all that should be left to do is plug the smoker into DP2 and the speaker into DP1