Remove the back cover from both the transmitter and the receiver for access to the code switches. Inside is a 10-bits dip switch exposed on the circuit board. Use a pencil or ball-point pen to set the 10-bits dip switch to the code of your choice.
For example, bits numbered 1, 3, 5, 7, 9 are set to ON, bits numbered 2, 4, 6, 8, 10 are OFF in the transmitter as below:
Then, to match the code of the transmitter, set the same bits numbered at ON/OFF position as the corresponding bits in the receiver as above example.
Be sure both are set to the same code, since a different setting of just one dip switch will prevent operation.