this is a difficult subject mate not many people have done it, as far as i know only GM who lives in ireland has sucessfully fitted fogs without fiat's help
firstly u need the switch pannel to go in the dash if you are locky you will get one from a breakers yard, if not then you will have to buy one from fiat.
the offside fog light has a wire to connect but you also need a length of wire to connect both fog lights and you need to fuse them i believe.
i have fog lights on my car but like you i don't have them wired up i just bought the bumper with the holes so i put fog lights in, one day i will get them wired up, but it isnt foggy in Hull so i don't need them
last time i drove in fog was when i went to ugc on kingswood about 18months ago, because there are no high buildings around that area the fog was just unbelievable, i couldent see 15ft infront of my car, lol it was madness, that was a time when i could have really done with some fogs !
I ended up getting all the parts new from fiat at a cost of nearly 500euro, which was a tad pricey. You'll need a relay which goes behind the glovebox, and the wiring on the bumper runs only to here, so you'll need to run a wire from there to the switch panel. Mine was a 97 1.4sx so yours may be different if its a mk2. Anyway i can give you a list of parts you'll need if you want to stick to official fiat parts.
I know its nivce ot have fiat parts, but a switch is a simply part, and its easy enought to run a wire through and you can buy the relay in a fog light fitting kit from halfords or similiar for a small price!