If there is no mention of fog lights, then they were not offered. This means
that a previous owner installed them, and you should be able to trace the
wires from the lamps back to the power source. There should be a fuse in the
line that you are following.
On my F150, I pull the light switch out to turn the fog lights on. The light
switch turns to power the main lights, and pulls to power the fogs. The main
lights must be on in order to switch the fogs on. Fogs are designed to
switch off when the high beams are activated. You do not want high beams in
foggy conditions, so there is no reason to have the fog lights on and the
high beams on at the same time.
Since the Ranger is technically a Mazda and not a Ford, then the light
switch might be different than what I have on my F150. But, it never hurts
to pull the light switch to turn the fogs on if the light switch is one that
you rotate to power the main lights.