Turn the headlight switch to the "On" position. The headlight switch is usually located on the right side of the steering wheel. It has three positions: "Off," "On," and "Auto." Turn the switch to the "On" position to turn on the headlights.
The foglights will now be on. The foglights will remain on until you turn them off or turn off the headlights.
Note: Some Jeep Liberties may have a separate switch for the rear foglights. If your Jeep Liberty has this switch, you will need to turn it on in addition to the front foglight switch.