Trowel on drywall compound to 1/8-inch thickness on walls or ceiling. Work in small sections so you can texture the compound before it starts to dry.
One possible way to create texture is by using a paint roller. Roll over the compound with a nappy roller. You can also apply the compound with a roller, but you have to mix the compound yourself and make it thinner than the pre-mixed. Then you can roll it on as you would paint.
Another way to create texture is by using a paint brush. Push the brush into the compound and twist. Move down your wall a few steps and repeat. When you are finished with the section, add more compound to the wall and blend in with the brush technique.
Use rags to create a wall texture. Roll up the rag in your hand and push onto the compound that is on the wall in various spots. Then roll a different rag and push into the compound on the wall to fill in between those spots. When you put more compound on the wall in a new section, start over with the first rag and move on to the second. Repeat until the room is finished.
A stencil also creates an interesting texture, but it is more difficult to use. You can make a stencil out of anything from a cookie cutter to a block of wood. Press the stencil into the compound in a pattern. You can go around doors and windows or outline a room. Then you can fill in with one of the other textures and paint.
Allow the compound to dry for 24 to 48 hours and then paint the room. Try to keep everything away from the compound until it is painted as it is powdery and will wipe off easily.