Install a switch in the cab of your truck in a location that is convenient for you to reach, or tap into the hid bulbs circuit of the hid headlights to power the relay. Mount the relay inside the cab, under the dash or other location out of the way and out of the elements. Relays are easy to install and some hid lights come with them, but if not, you can pick up a relay from your local auto parts store.
Most off-road lights draw a lot of power when switching them on, and this load should never be applied directly to the switch. Using a relay for the switching duties will save your switch and lights as well as make for a safer installation. Installing off-road hid lights on your truck will improve your vision at night. But make sure you only operate them off-road.
This is the positive feed to switch the relay on. You will also need to run a ground wire to the switch from the frame or other ground then run a positive feed wire from the battery to the positive in position on the relay. Find the ground position on the relay and run a wire from it to a good ground on the chassis of the vehicle. Anywhere on the frame or other metal structure of the vehicle will normally produce a decent ground. HID bulbs stands for high intensity discharge, which refers to a new technology that relies on an electrical charge to light the xenon gas contained in a sealed bulb. Unlike the hid bulb, the HID bulb does not have a filament; because there is no filament the bulbs are not susceptible to vehicle vibration damage. They are, however, affected by fluctuations in the vehicle's electrical system, and depending on the vehicle, they may require some resistors. Thehid bulbs creates light by bridging an arc between two electrodes, instead of heating a filament.

Run a section of wire from the switch output to the switched power input on the relay. Again, this will be marked or identified on the directions that came with your relay. There will be four connectors on the relay, a positive, a negative, a positive out and a positive in from the battery. Read the packaging or directions to determine which is which.