You will need a relay, and a switch. The best way to wire it up is to have it powered by your high beam circuit. Then when you dip your lights for oncoming traffic the spotty will go off as well.
I'm not sure how my fogs are wired up, but they are using the same circuit as high beam with a relay. I set it up to run a pair of halogen driving lights but changed my mind and replaced them with the foggies.
From memory, you have your power coming from somwhere at the back of the fuse box to the relay. Then out of the relay to the light. Then you have a lead from the relay to the switch. And then I think a lead from the high beam wire to the relay.
It is all set up so that the big amps required to run the light don't go through the switch, just through the relay. The power from the switch to the relay just trips it to make a circuit.
When you buy the relay, make sure it comes with a wiring diagram, they are reasonably easy to follow. I managed without too much trouble.
Another thing to make sure of is that your generator/alternator is pumping out enough power to run the extra light. It might drain your battery otherwise and you might end up in the dark.
