Replacing a door lockset makes an old door look and feel completely different. The whole job takes about 20 minutes.
Unscrew the two screws on the inside knob and pull both knobs apart. Remove the latch plate screws from the door edge and slide the latch out.
Slide the new latch into the door edge with the curved face pointing toward the direction the door closes. Line up the outside knob, insert the spindle, attach the inside knob, and thread in the long screws.
Install the new strike plate and confirm the latch lines up cleanly. Close the door and turn the knob from both sides. Lock and unlock it. If it sticks, adjust the strike plate slightly.