Remove the screen door from the hinges
Lay the door on a flat surface
Remove the old screen spline with a screwdriver or spline roller
Pull out the old screen material
Clean the frame and spline groove
Cut the new screen material slightly larger than the frame
Lay the new screen over the frame
Press the screen into the groove with a spline roller
Install new spline around the frame
Trim the excess screen with a utility knife
Rehang the screen door
Test the door for proper fit and operation