Remove the seat of the chair with the screwdriver. There will be small screws on the bottom of the chair that will unscrew.
Remove the staples with the staple remover. Depending on which type you have it may pry them off or it may be a clamp model.
Remove the old batting. Place the new batting on the top of the seat. Cut around the seat with the scissors.
Flip the seat over and staple each of the four corners once. Pull the original seat cover tight and place a staple every inch. Continue around the seat until it is stapled down.
Screw the seat back on to the chair frame.