How to configure cubemaps?

Hello to all! I have a small problem with a cubemaps, I don’t understand how it works. Could you help me a little with this, or show me a place where I can read how they work in playcanvas?
I don’t know English (I use Google translator), so it’s hard for me to search for information on it. Thanks in advance for your help.
The project in which I will try to set up reflections: PlayCanvas | HTML5 Game Engine

This manual describes how to work with cubemap in playcanvas. In this example, you can see the installed sky box in the project.