Assuming you are talking about how to engage your 4 wheel drive on a car, there are generally two ways to do so. The first way is by manually engaging the four-wheel drive system using a lever or switch inside the vehicle. This must be done while the car is not in motion. The second way is by engaging the system while the car is already in motion. This can be done by pressing a button or turning a knob inside the vehicle while driving at low speeds (<5 mph).