Missing a brief overview of how it works and a short demonstration

You might not believe it:

Today is the first day that I have read about processing.
So I looked up the homepage.

Lot's of information but nowhere I could find a still brief description that goes beyond

"Interactive programs with 2D, 3D, PDF, or SVG output"

aha. --- .. --- ... --- ... and how is it "processed"?????

Do I click drag and drop graphical objects that represent computing commands?
Do I write a programtext? similar to which programming language?

Where can I find a graphic that gives on overview about the main elements used by processing?

The homepage suffers from "experts blindness to beginners diffculties"

首先查看 processing.org 主页及其现有的学习资源，以了解简要概述和演示适合放在哪里。完成的标准是：添加一段简洁的说明，介绍 Processing 的使用方式、用户编写或操作的内容，以及一个能够回答 issue 中新手问题的简短演示。