Grip the trowel firmly in your hand. Add joint compound to the smooth surface. Press the straight edge of the trowel against the ceiling. Tilt the trowel at about a 45-degree angle.
Swipe the plaster onto the ceiling. Once applied, take the trowel and stamp into the plaster with the smooth portion of the blade. This creates peaks forming from the joint compound.
Use the edge of the blade and skim the peaks of wet plaster to knock them down. Move the trowel around the surface to form valley and ridges in the plaster. Continue the process until the entire ceiling is textured.