At first glance, this is an elementary procedure. However, in practice, things are not so simple. Personally, I really regretted that when I bought the film for iPhone I refused the seller's services to stick it on right there. Any dust and even the slightest displacement leads to terrible results. But the most irritating are air bubbles left under the film as a result of incorrect pressing. And with each new attempt, the bubbles and dust only grow. Thus, the case for 30 seconds develops into a lost half hour. And then there is a trip to the store for the second film. Here's a video on how to do everything the first time. It uses two pieces of adhesive tape, so the film on the iphone is much easier to align and stick to the screen of the device.