How do widgets work in VR?

First off, I’m working from the VR template. I’ve been trying to build a control panel with a series of buttons you can go up and press for different effects like changing scenes for a environment visualization project. I make some widgets but can’t find any tutorials on how to trigger them. Or at least, I find tutorials from 2015 or older that don’t work.

make sure that you researching about 3d widget: