Make Minecraft HD skin yourself?

So I have two questions. The one:

How can you make your own HD skin? Can you easily do this in a drawing program, or how does it work?

Second, how do you upload that in Minecraft? Important: Java, latest Minecraft version!

Jup → https://www.minecraftskins.com/skin-editor/

Install skins in the Minecraft Launcher under "Skins"

But that's not for HD skins, is it? 😬🤔