After you've connected the wires, install the Base to the gang box.
Be sure to check that the "Up" sign on the front of the Base is facing the right way, and tuck the wires into the gang box. Then, attach the Base using the two screws provided. Make sure you use our flathead screws, and not your existing ones.
Tighten the screws until the point where the plate is held securely to the wall, but do not over-tighten. If you're a numbers person, this should be 10-12 inch-pounds of torque. The plate has strain reliefs that are designed to bend to accommodate differences in gang box styles and mountings. Some bending of the strain reliefs is normal, and not required for a secure fit. Over-tightening may result in Faceplate mounting issues.