you rig up the LED strip in the housing. you plug it into its transformer, if it has one, or it might already be hooked up to it. then you take the positive and negative wires from the transformer, again...if there is one, and hook them up to the positive and negative wires that turn on that little bulb that goes in the bottom of the headlights.
good luck. i wouldnt recommend doing something like this for the first time, especially on your own. and especially you.