Remove the drawer from the drawer opening and set it aside. Look into the drawer opening and locate the bottom drawer runner.
Locate the mounting screws in the bottom drawer runner. Unscrew the mounting screws from the worn bottom drawer runner using a screwdriver.
Remove the screws from the mounting holes in the worn bottom runner and take the runner out of the bottom of the drawer opening.
Lay the replacement wooden drawer runner in place of the removed drawer runner. Position the runner in the same way as the runner that you removed.
Drive the screws included with the replacement runner through the mounting holes into the bottom of the drawer opening with a screwdriver. Replace the drawer into the drawer opening.