How do I replace the air cleaner on my engine?

To remove a flat air filter, loosen screw and tilt cover down to take out cartridge; install new clean cartridge with pre-cleaner lip at bottom of cartridge pleats. Insert tabs into slots on base and tighten screws. For oval cleaner: Loosen two screws lift off cover, replace with new cartridges then put cover back tightening the screws (Pages 17-18).