Cover the floors and walls with plastic dropcloths. Use painter's tape to adhere the plastic to the walls. Applying texture is a messy job, so you should protect the floors and walls in the room from splatter. Cover any furniture that you cannot remove from the room.
Mix water with premixed joint compound in a 5-gallon plastic bucket. Use an electric drill with a stirring bit installed to make it easier to mix. Mix the joint compound until it is the consistency of thick wallpaper paste.
Screw a broom handle into the end of a paint roller applicator and insert the applicator into a longer nap roller.
Dip the paint roller into the bucket of joint compound until it is completely submerged. Pull the roller out of the joint compound and tap the handle of the applicator on the edge of the bucket to remove excess compound.
Begin rolling on the joint compound in a corner of the room and work your way across the ceiling and over to the other side. Dip the roller into the joint compound frequently to ensure that you are applying a thick coat to the ceiling. Apply a coating to the entire ceiling before you begin to texture.
Use a trowel or another chosen delivery method to apply the texture. Start in a corner on one end of the room and work your way across the room to the other end. It may take several attempts to get the hang of applying the texture with your chosen method. If you make a mistake, simply roll on more texture in that spot and try again. Eventually, you will become proficient. Let the joint compound dry for at least 24 hours before painting.