Need help creating a dimmer (HELP)

:beard: I am working on a project where i have to dim a room scene with a dimmer switch.

The idea to take a dark room scene and make it light up
User interaction the user will be able to click on a dimmer and increase the brightness or darkness of the room.

The problem i am not sure how to script the dimmer to increase or decrease the light. If anyone know that would be great.

thanks