First with a wet towel on the glass dust wipe (not too dry), and then sprinkle the water on the glass, even some (if you use a small spray watering effect will be better), cellophane paper to cut, sprinkle a little water, gently can be put up, if not right can be hand push, or lift up and start again, two or three days do not move it, so it is natural to do it Everything will be fine..
The thing to note is that water must be used around windows. If this happens, it will not be sticked around very quickly. If it doesn't fit, it will be easy to uncover. If there is any bubble, it must be squeezed out.