Don't know how to dim the display (Ubuntu)

1. Go to the System Settings
   
   There are several ways to access the system settings:
   
   
   • From the Ubuntu taskbar
     
     

     
     
     

   • By typing system settings in the Unity dash search box
     
     

     
     
     

   • By clicking the wheel in the top-right corner of the screen and selecting System Settings
     
     

     
     
     

2. Select Brightness and Lock
   
   

   
   
   

3. Move the slider to the left to decrease the brightness level
   
   

   

    

Note: If you don’t like to go to the System Settings to adjust the brightness every time, or if your laptop doesn’t come with a dedicated brightness control button, you can install the indicator-brightness utility to directly adjust the screen brightness from your desktop.

To install it:

1. Open the terminal by pressing Ctrl + Alt + T
   
   

   

   
   
2. In the terminal window type the following lines (one by one, i.e. once you enter the first line, press Enter, and repeat the same procedure for the other lines):
   
   sudo add-apt-repository ppa:indicator-brightness/ppa
   
   sudo apt-get update
   
   sudo apt-get install indicator-brightness
   
   

   
   
   

3. After you install it, you can adjust the brightness from the desktop, by clicking the sun icon, and selecting a value which will suit your needs