Remove the old drum head by using the drum key and turning the lug nuts counter-clockwise. Peel the original drum head off the tom and set it aside. You may want to use it again later, so keep it in a safe place.
Replace the old drum head with the oil-filled drum head. Make sure to line the drum head up along the rim of the tom.
Put the lugs back on the screws and tighten them in the same way you would put a wheel on a car. You want to move from one screw to the screw on the opposite side. Tighten them with your hand -- do not use the drum key.
Tighten each of the lugs until all of the kinks in the drum head have been removed. Once the surface of the drum head feels smooth, turn the drum key one quarter turn counter-clockwise on each of the lugs to slightly lower the sound.