Article: Fit the teeth of the hinge on the door with the teeth of the hinge on the door frame. Have someone hold the door in place as you attach it to the door frame with screws. If your hinge has screws, use the same ones you removed to reattach the hinge to the door. If it has hinge pins, insert the pins into the interlocking teeth from the top of the hinge and tap them in with a hammer. Hammering in the hinge pins will attach the door to your door frame. Take your doorknob and place it into the doorknob hole. Secure it to both sides of the door with screws and make sure that it works properly. If you've done everything correctly, your new door should be installed!

What is a summary?
Hang the new door in the doorframe. Screw in the hinges or reinsert your hinge pins. Install your new door knob.