Cover any furniture, flooring or items with drop cloths that are below the area being cleaned. This will protect them from damage.
Add two cups of warm water to a spray bottle. Depending on the size of the stain, add more water to make more solution.
Mix two to three squirts of a mild detergent into the warm water in the spray bottle. Place the lid on the spray bottle and shake to mix the solution.
Ascend the step ladder and spray the solution onto the stain. Saturate the stain but avoid the clean areas around the stain.
Dab the stained area with a damp cloth to lift the stain from the ceiling. Do not scrub or rub the area as this will cause the popcorn texture to flake.
Allow the area to dry. If the stain is still visible, repeat Steps 1 through 4.