Help mysensors, arduino and home assistant

Guys
I have two arudinos connected to the RPI with home assistant. I am trying to connect another arduino with pressbutton and led through the usb serial with mysensors. It turns out that I have not been successful, I saw the tutorials but I confess not that I am not understanding much. If you can help me with a simple arduino sketch so I click on the button and the led goes up through the mysensors I would be very happy