If you remove the vent trim from the ceiling and look or feel in the gap you should find the loose wires laying there.
Not all vents are pre-wired for a vent fan, in those cases you might connect to a light close by. If the light has a switch on the wall it will have to be on to use the fan. As long as the light fixture has a switch on it, that will work fine, if not then you will have to install a new fixture with a built-in switch or install a switch at the fixture yourself.
Richard & Jill
2014 Flagstaff 832IKBS Classic Super Lite
2018 Silverado 1500 Crew Cab Z71 4WD All Star Edition
Camping since 1989, seasonal since 2000
Car Shredder Op/Tech, Scrap Metal Recycling - retired
The Faster I Go, The Behinder I Get.