Turn off electricity to the existing light fixture at the wall switch and at the house fuse or circuit breaker box.
Remove the screws that holding the existing fixture to the ceiling. Lower the fixture, so you can disconnect the wires above it. Remove the fixture completely, leaving an exposed electrical box in the ceiling with three exposed wires hanging from it: a black insulated wire, a white insulated wire, and a bare copper ground wire.
Hold the installation bracket that came with the new light up to the electrical box, lining up the holes for the provided screws. Secure the bracket to the box using the screws.
Twist the copper grounding wire around the green grounding screw on the installation bracket. Tighten the screw.
Set the new light fixture near the box, on top of your ladder. Hold the white wire from the light next to the white wire from the box and twist a wire nut over the ends of both of them at once, covering all exposed parts of the wires.
Link the black wire from the light and the black wire from the box in the same way and secure with a wire nut.
Hold the light up to the box, while tucking the two wire connections into it. Secure the light fixture to the electrical box with the screws that came with the light. Turn on the electricity.