electric fan

hey guys my buddy has a 1969 and it has an eletric fan but the dumbasses that had it before him literally spliced one of the wires to the alternator and put in the fan lol i was just trying to find out where do you wire the fan to? we looked at mine and followed the wire to inside the firewall but i dont know from there.. i assumed you would do it to the started but the wires are only like 2 foot long from the fan at best.. i told him the best option would be to prolly run it to a switch and put a switch inside the car