The driver would load your car onto the open car carrier trailer.
If the car is inoperable, a winch may be needed to load your vehicle otherwise the driver would simply drive your car onto the trailer. Your car would then be strapped down by the wheelbase to the frame of the open carrier trailer making sure that it's secured in its spot. This is done to stabilize the car down as the road can get rather bumpy sometimes. Once the loading process is complete, the driver should be on his way to delivering your vehicle to its state to state destination.