Door closer adjustment is an art that requires knowledge, patience, and a wrench, hex key or screwdriver. To adjust the door closer, use a step ladder to reach the door closer. Examine the closer. If you cannot see the adjustment screws, the closer has a cover. If you see no fasteners holding the cover, the cover is held by tension. Pull it off. If you do see fasteners, loosen, do not remove, the fasteners and the cover will slide off. The adjustment screws are marked or there will be a diagram inside the cover. Start with no more than 1/8 of a turn of the adjustment screw clockwise, and counter-clockwise to speed it up. Then test the door.