Layers and the Mask
The heart of Photoshop is the ability to use layers to do various things you couldn’t do any other way. Typically using the masking function to bring in something from lower layers.
Some artists out there get very detailed with layers and might have 20-30 layers all going at once. Each layer being some element of an image where they may need to change colors, size, or angles of items within the different layers. There are easy ways to group layers within folders as you work with them. I didn’t demonstrate that in the video, but if you end up working with a bunch of layers you should know you can do that. And certainly name your layers so you know which one is a head, an arm, background, etc. Having everything organized is very important to your sanity.
Of course I touch on compositing because that’s how I use the layers and masks for the most myself.
I have used layers in conjunction with liquify to fix serious blemishes. Here’s a link to that.
Here are a few files to help you practice layers and masking.