In this guide I'll be using the ArtStudio app to show how to use layers. But the same principles apply to all image editors that support layers.
Think of layers as sheets of either paper or sheets of clear plastic. Imagine a drawing on a white sheet of paper. Then a drawing on a sheet of clear plastic. Then place the plastic sheet on the paper
That would be the same thing as layers in an image editor. The only difference is the layers are digital layers.
Well that covers the basics of layers. There is more to know but this is the basics. I hope someone finds this helpful. Feel free to ask any questions you might have.