Do you need to know how to code?

No.

You describe what you want and PlugThis writes the code. A real example of a complete instruction:

> Build me an extension that highlights all email addresses on any webpage.

That's the whole input. Nothing else is required.

If you do know how to code

You can download the source and edit it directly. Nothing is obfuscated or locked, and there's no proprietary format in the way. It's ordinary Chrome extension code, laid out the way you'd expect.