Red wires go to 5V, black wires to Ground and the Yellow go to pins C0 to C5.
Two LED turn at the same time as the motors. This was really useful for debugging.
There are 2 sources of power, the strip on the lower part of the picture is 5V passing
through a rectifier, the strip at the top of the picture has the power straight from
the source. Two transistors act as switches to turn the motor on and off. The speed of
the motor is given by PWM.