Open the door and inspect the old weather stripping
Remove the old weather stripping from the door frame or door edge
Clean the surface thoroughly
Measure the door frame or door edge
Cut the new weather stripping to the correct length
Fit the new weather stripping into place
Press or nail the weather stripping securely
Check for gaps around the door
Trim any excess material
Close the door and test the seal
Adjust or replace any loose sections if needed