Windows Project/Display Settings
When you are using a projector or a second monitor, you have multiple options as to how you would like to project to the second screen. To access these settings and toggle through them, press the windows key(looks like the windows icon) + P.
The first option is PC Screen only, which will leave the second screen blank and only have your PC screen on.
The second option is Duplicate, which will have the second screen mirror your PC screen.
The third option is Extend, which allows you to display different things on each screen. By default, to get to the second screen, it is connected through the right half of your screen, so you would move your mouse through the right side of your screen. You can change this by typing in display settings in the lower left search bar and hitting enter. You will see Rearrange your displays and your projector/second monitor will appear as number 2. Click this and drag it to however you would like it to be connected to your first screen.
The fourth option to display is Second Screen Only, which will only display on your second screen and leave your PC blank.