I'm a beginner in UI right now and I wanted to upload my work on Behance. But I want to put my project images on the iPhone screen mock-up. I did know basic things about it but still confused about how to do it particularly. I'm putting some images down here, I wanted to do as same what is there in images.
You will need to have Photoshop installed. These are mainly photoshop mockups with smart objects inside them. You will need to edit those smart layers and save the smart layer. They will update automatically in the design file.
You can find such files here, they are free to download: https://graphicburger.com/mock-ups/