How do I fold down the back of the back seat

In the middle of the seat cushions in the back of the seat there is a little loop, pull that loop forward and that will have the seat's bottom pulled down to the floor agains the back of the front seats. Next simply pull hard on the back of the back seats and the seats should fold down nicely into the open space. Be sure to remove the headrests so the seat will fold all the way down.