Locate the breaker in the main electrical panel supplying power to the light pack fixture junction box.
Unscrew any cover plates or old lighting, using the Philips screwdriver. Some external lighting fixtures simply have cosmetic nuts that can be removed by hand. Rotate these counterclockwise, until the fixture (if applicable) comes loose.
Locate the white, ground and black wires inside the junction box. Unscrew any wire nuts that may be connecting an existing light fixture from the wires. Leave only the three wires in the junction box.
Find the black, white, and green/bare ground wire protruding from the back of the new light pack fixture. Place the ground, black hot and white neutral wires parallel with one another. Rotate a wire nut over the each pairing sequentially until hand-tight.
Screw the fixture to the holes on the junction box, as specified by the manufacturer.