How can I make buttons in VR. and assign some actions on ray click?

I see lots info, classes, but no full examples and normal docs..

especially after v74 meta change.

I found 2 variants:

1. RayInteractible - on target object. and RayInteractor on controller. https://developers.meta.com/horizon/documentation/unity/unity-isdk-create-ray-interactions/#add-ray-interactors

- not clear how to add actions on click??

2.canvas  https://developers.meta.com/horizon/documentation/unity/unity-isdk-create-ui/   

- also not clear how to add logic to it

I don't understand main unity architecture. So, appreciate any suggestions.

Thank you in advance!