With the bumpers in this low-profile position, expand the dog gate to fit your doorway or stairs and screw in the adjustment knobs that are on the gate itself. The gate may not even stand in place by itself, don't worry, just get the best fit you can.
Now, holding the gate in place, start screwing those big knobs on the bumpers toward the center of the gate--not toward the wall. This is what exerts the pressure to hold the gate in place.