Make sure the paint on the car is thoroughly cured before applying the window material.
Use a piece of paper and scissors to create templates for your car windows. Make sure the templates fit as desired before tracing and cutting the window material.
Turn the templates over and trace them onto the back of the window material. Cut out the windows from the material with sharp scissors.
Peel off the backing material and apply to the car. If needed, you can remove and reapply a few times to get the window positioned properly.
Use a soft rag to rub out any air bubbles.
After 24 hours, the backing adhesive will cure making it difficult to remove. If desired, you can apply a clear coat over the window material.