Janek's all download site/dev/extension
start by downloading Website Builder
1.
2.
open files in the extend folder named load.Json and in the test folder open run.json
3.
in load change the "folder" to ex.my extension

And in run.json if you changed yours folder name you need to change the path to extend/my extension
4. optional
in run.json you can change the "changeicons" to true if you want to make your own textures for the menu or to false if you dont want do do that

* they need to be 32x32 pixels
to use your icons simply change the icons name to ex. prerun.png and replace the old one in the extension folder
5. optional
also you can change text, backgrounds and sidebars to the color that you want. You can also use HEX ex. #330066 as a color
and you can change the font to your liking
6. share
you can share your extension by sending someone the load.json file and your folder and files in it
In the future i will make a program that will do that for you
Just wait