The Max Buzz's screen is dimmed when not in use. The screen will "wake up" automatically when you lift your wrist that the Max Buzz is worn on, and turn it towards your body. As the Max Buzz remains in that position, tap on the screen to move through the different displays (click here to see a list of the screens!).
You will be able to set the "Wearing Mode" for your Max Buzz where you indicate on which wrist you'll be wearing your device. This controls the direction that the Buzz must be turned in order to activate the screen.
Check out the "How to set the wearing mode on the Max Buzz?" article for more information!