Trouble with board group menu features

Hi I am new to Monday.com app development but I was able to upload my first app → the view tutorial, hooray!

However, I would like to develop an app for the board group menu feature: Board menu features

I am having some trouble where to start. How does the core structure of the Javascript need to look like.

Can you guide me in the right direction?

What I would like to do is to duplicate a group. I know there is a button for this but I want to develop it myself as a learning opportunity.