How to show and unshow a cockpit control overlay programatically

I need to write software to show and unshow an overlay to highlight a cockpit control. This will be in response to a physcial input i.e. press a button on a usb box to highlight e.g. an A320 FCU speed knob. It’s already been done in the tutorials & I’ve included a screenshot. In case I can’t use the existing overlays (suggested by a response already), a further question is : - how would I place my own artwork?

Picture1

I’m looking for information about what I need to do, not necessarily how to do it. I am programming literate but don’t understand the MSFS 2020 development ecosystem so pointers towards tutorials and relevant material are particularly welcome.

How might I create the software that sits in the middle, reading the USB button’s input and displaying the overlay in the cockpit in response? Wading through the SDK and forums, I’m feeling quite lost!

Thanks,
Paul.