how do i make a theme for gdevelop?

I wanted to test if some colors would look good on gdevelop, but I don’t know how to do that, I modified the colors in a file I found on the website https://github.com/4ian/GDevelop/blob/master/newIDE/README- themes.md
and put the colors I wanted, but I don’t know how I can see how it looks, does anyone know what I can do? I am not a programmer.``https://drive.google.com/file/d/1yz2XuW3p4RwPbVLTw8BuQXdIpbOTuAmM/view?usp=sharing the file I said