Take off the old doorknob by removing the two screws in the front of the doorknob plate. The two pieces of the doorknob will pull easily away from the door.
Remove the latch assembly, the part of the old doorknob still attached to the door, by unscrewing the latch plate from the door. Then insert the screwdriver into the assembly and, using the screwdriver as leverage, carefully push the assembly out of the door.
Slide the new latch assembly into the door and hold the plate firmly against the door. Mark out its position with a pencil. Be sure you can clearly see the complete outline. The installed plate must be flush to the door. Remove the latch assembly and use the chisel to carve out the outlined latch plate area to about 1/16-inch depth. Replace the new latch assembly and screw in place.
Insert the new doorknob through the latch assembly. Ensure the lock is on the inside of the door. The other half of the knob fits over the prongs on the side you inserted first. Line up the screws and tighten it down.
Replace the old strike plate, the piece attached to the door frame, by removing the screws and gently prying with the screwdriver.
Set the new strike plate over the existing holes and screw it in place.