if you want easy, run a wire directly from the battery positive, into a fuse, into the switch and then back out to the foglamps, and ground the foglamps to a bolt or nut by where they are mounted. if the switch needs to be grounded (like if there is a little light bulb inside it), ground it in the dash.
if you run the foglamps directly off the parking lights you could possibly fry your electrical wiring - not the wires you just installed - but the engine harness.
the reason for the complexity is that the foglamps use a lot of power and the electrical wiring inside the car may not be thick enough to handle all the extra load and may start to get hot like the filament in an electric heater.
if you would like to have them controlled from the parking lamps you need to use an automotive relay. You can power the relay off a tap from the parking lights, but you still need to get power off the battery plus.
-or-
get a foglight installation kit, most of this stuff should be in it already.
good luck!