Every edit you make in Photoshop lives on a layer, and the way you stack, mask, and merge those layers decides whether you can change your mind an hour later. If you've ever flattened a file to run a filter and then wished you could go back and fix the retouching underneath, you already know what a shaky grasp of the Layers panel costs. Plenty of people treat layers as something to figure out later, once the basics feel comfortable. Unmesh Dinda of PiXimperfect takes the opposite view, calling the Layers panel the heart of Photoshop and building a long beginner lesson around it. He starts…