Turn off the electricity to the ceiling electrical box. If there's currently a fixture attached to it, remove the fixture using your screwdriver. Disconnect the three wires from the fixture and leave them hanging from the box. You will see a black wire, a white wire and a bare copper ground wire.
Find the mounting bracket for your new light. It will be a flat metal piece with a green grounding screw on it, and open screw holes to attach it to the box. Attach it using the provided machine screws.
Take the end of the bare copper ground wire and bend it into a U-shape, using your needle-nose pliers. Hook it around the green screw. Tighten the screw.
Raise the new light to the electrical box. Hold the white wire from the light next to the white wire from the box and twist a wire cap over the two of them. Do the same for the black wires from the light and box.
Tuck the two wires up inside the box. Mount the light to the mounting plate, using the provided screws. The green grounding screw and copper wire should be completely hidden by the fixture. Turn the power back on.