How to create a Chrome extension full sidebar?

👋 Hi

I'm new to coding. I'm a product designer starting to learn to code to help me build my ideas come to life.

I am practicing building a Chrome extension. I'm not getting anywhere, tried to ask on X too but had no luck finding the answer to this question.

How do you create a Chrome extension full sidebar? Just like the attached image (an example)? What do I need to do?

I appreciate the good souls! :)