Well you have two wires soldered onto your motor. Those two wires need to be switched around.You may switch them at the point that they meet the motor, or you may switch them where they are soldered to the board. You could even cut the wires and solder one to the other. You sort of have a (+) charge going to the (-) side of the motor and a (-) charge going to the (+) side of the motor if that makes more sense.