Open up the car trunk. Remove the panels to get access to the light bulb connectors.
Locate the factory -T- connector that is most likely around the bulb area.
Get your wiring harness. Plug the connector on the wiring harness to the -T- connector.
Now you need to ground the wiring harness. Find a good spot on the vehicle and ground it there.
Do the passenger side now. Put the panels back up and put the trunk carpet back in its place.
Test the wiring harness to make sure it works. That's it, you are pretty much done. When you want to use the wiring harness, just open the trunk and take the connector out. Don't place the wiring on the latch of the trunk as it will get damaged when you close the trunk.