Before you start, turn off the power to the light at the breaker. Then loosen the screws on the front of the light fixture to pop the light off the wall and reveal the wires behind the light. Unscrew the wire nuts attaching the wires starting with the ground wire first (no plastic coating), then the neutral wire (white), and lastly the live wire (black). For more details, check out this tutorial and video for how to install a vanity light.