That’s okay! I think all digital drawing drawing apps have layers. Different people use different layers for different things. Some people may use one for the hands and one for the nose. I kinda group all the skin together because they’re all kinda similar in coloring and shading and have a sketch layer and a flat skin color layer and multiple skin shading layers. It really depends on the person. I have an eye layer and a hair layer and a background layer and etc. That’s how I group my layers, but some people may do it differently. I came to digital art from traditional, so I actually enjoyed using only one layer because it felt more natural to me because there aren’t layers in traditional art. I think the best way to separate your layers is whatever works best for you. I can’t think of any videos or websites off the top of my head, I kinda had to learn through experience by myself over time. I hope this helps! 