When you have water damage, or a wild swing from a hockey stick that forces you to repair the stipple on your ceiling, the repair is a combination of art work and home improvement technique. You probably won't match the colour, even if it is just because the old one is dirty and the new clean, so plan to paint over the patch when finished, and don't forget that primer sealer on the new plaster.
When you go to the store you will note that there are two or three different textures available, each with different size grains. Study your ceiling carefully to choose the right texture.
The tricks to success are to moisten the ceiling first, then force a fair amount of the stipple onto the ceiling to assure good adhesion. Then choose a tool that resembles the pattern on the ceiling. Sweeping strokes are probably made by bristle brushes, peaks are made by sponges. The rougher the surface texture, the rougher the sponge surface. Now moisten the tool and force some of the stipple into / onto the tool. You need the stipple well stuck to the ceiling and well stuck to the tool, then you push the two together and pull them apart and you will start to get the pattern you are looking for. Now comes the art. Find the touch that creates what is already on the ceiling. If you aren't getting it, scrape it all off before it sets and start over.