If you want them to turn on and off independently from anything else at the back of your truck, you will need to run a power wire from your switch all the way back to the lights, and then from the lights to a good ground.

You can power the switch to either come on when the truck is running, or at any time, regardless of the truck running, it would depend on where you pull your power source from.

If you want the lights to come on at any time, regardless of the truck running or not, you can pull the power from the battery + terminal. I would suggest you add an inline fuse (2-3 amp is big enough, certainly 5 or less) right off the battery, in case something might get cut or shorted out some time, then run a wire to the + side of the switch for your new lights.

If you only want the lights to come on when the truck is running (or the key is in the on position), you will have to use a test light to find a power wire off your fuse panel that turns on and off with the ignition switch. I would still add an inline fuse, then run a wire to the + side of your new switch. The inline fuse is simply to protect the truck wiring if the wires or led lights should get shorted out to ground.

Led lights don't pull very much power, heavy gauge wires will not be required, 20 or 22 gauge wire will be big enough unless you have a bunch of led lights connected to the wires.

Your going to need enough wire (I'd use red or pink) to run power to the inline fuse and then to the switch, then to the lights, then enough (I'd use black) wire to run from the lights to the ground. You will need enough connectors to connect to your power source (battery, or ignition powered wire), to connect to both sides of the inline fuse, and to both sides of the switch, and to connect to both wires of the lights, and terminals to connect to your ground. You will need a switch, and the inline fuse.

I would consider a switch that will light up when its turned on, so you will know when its on. It will add a couple more steps to add the light, but would be worth the effort. Gene