Step 1: Clean the window thoroughly, and make sure the surface is smooth. Step 2: Measure the window. Step 3: Cut the window film. You can cut about an inch more than the size of the window. Step 4: Remove the protective film. Use the tapes that come with the film to stick to the front and back of a corner, and then tear off carefully. Normal tape has the same effect. Step 5: Spray a lot of soapy water on the window and the back of the film (the side with glue). Enough water helps to adjust the position of the film and expel air. Step 6: Put the film on the window. Spray some water on the front of the window film. Step 7: Use a squeegee to squeeze out the air inside from the middle to all around. Step 8: Cut off extra film alone the edge of the window frame and wipe off excess water.