Instructions
Remove the cover over the SD card slot on the front of the console. This cover is the little door located next to the disc slot.
Press the sync button on the Wii console. This is the red button located next to the SD slot. Lights will begin to flash after you do this.
Press the sync button on the Retro Wireless Controller. This is the red button located on the back of the controller. This must be done within about 10 seconds after pressing the Wii sync button.
Wait for the lights on the Wii to stop flashing. This indicates that the sync is completed.