Measure the existing door and frame
Remove the old door from the hinges
Take off the hinge pins or unscrew the hinges
Remove the doorknob and latch hardware if reusing or replacing them
Inspect the frame for damage or rot
Repair or replace any damaged frame parts
Compare the new door to the old one
Mark hinge locations on the new door
Cut hinge mortises if needed
Drill holes for the doorknob and latch if needed
Attach the hinges to the new door
Place the new door into the frame
Secure the hinges to the frame
Check the door swing and alignment
Trim the door if it rubs or does not fit
Install the latch, strike plate, and doorknob
Test the door to make sure it opens, closes, and latches properly
Paint, stain, or finish the door if needed