Step 1: To drill screws holes on window frame, distance between each hole should be 30-40mm.
Step 2: To drill screws on the wall of window opening.
Step 3: To insert expansion bolt into the screw holes on the wall of window opening.
Step 4: To put the window into the window opening and fix the window by tightening the screws up.
Step 5: To fill the gap by foam or other materials if there have the gap between the wall and the window.