After you pull out the filter case. There is a tab on the bottom and on the top that holds the ends in undo these.lift out the combs and the filter. Open the new filter and hook it onto the tabs of the filter case and close the ends back up. Get one of the combs in all the cracks of the new filter then slide the next comb in right next to the one that is installed and slide it down to the furthest slot where the combs go. and do this for the rest of the combs until they are all inserted. once they are all in replace the filter case into the cavity be sure to line the slots up on the case and the cabinet and put the door back on.