Hi Joanne,

Other than mentioning that it's a Vauxhall, you've not given us any other information to go on. The process to do this will vary considerably by make, model, year, etc. Come back to us with those details and we can look into it for you. In general, there often is a subtle power button near the screen that you can hold down to turn it off, though sometimes this is hidden in the menu system. Look for settings relating to the display. You can usually reduce the brightness of it there as well.