Measure the length and width of the flat screen television. Tape several pieces of newspaper together to make a piece of paper the size of the flat screen to be used as a template. Center the paper over the fireplace. Move it around until you have the bottom of the paper at least 12 inches above the fireplace mantle. Tape the newspaper in place.
Move the stud finder across the wall above the fireplace and mark the paper everywhere you locate studs. Most homes have 16-inch spaces between studs.
Put the flat screen mounting plate system together according to the manufacturer's instructions. Most models come assembled unless it is for a flat screen television over 60 inches. There are two parts to the mounting system. One part is the plate that screws into the wall; the second part is the hook that mounts to the television.
Place the television mounting plate in the center of the newspaper on the wall and screw it to the wall through the pre-cut holes in the mounting plate. Ensure the screws go into the studs. Screw six to eight screws into the wall so it holds the plate firmly in place. Tear off all of the newspaper around the mounting plate.
Attach the mounting hook bracket that connects to the back side of the television into the center of the television. There is a spot in the center of the television designed for a mounting hook bracket.
Lift the television up so the hooks on the back of the television line up with the mounting plate on the wall. You need a second person for this part of the project. Hook it onto the wall mounting plate. Screw down the thumb screws on the mount on the back of the television. This locks the mount into place. Some models use a push pin for locking the mounting of the television in place.