I dont know what to do and im horrible with computers!
I am guessing the cut off part is PROJECTOR, and let me guess your confused on why it isn't showing?
If your running Window 10, in the bottom right is the icon to the right of the clock and date, click that then EXPAND above it if you can't see the icons. You will see one called PROJECT, and that is for PROJECTING the laptop's screen onto another screen. When you click on it, you will see the options, if you select DUPLICATE then what you see on your laptop is what shows on the PROJECTOR. If you select EXTEND, then you will extend the laptops screen to the RIGHT onto the PROJECT (move your mouse from left to right on the laptop and then you will see it 'slide onto' the Projector screen.
If the projector is NOT showing any image you need to use the projectors menu to SELECT the HDMI source. Honestly this is all a IN PERSON thing, I would suggest asking a more technically minded colleague, staff, or maybe one of the kids to shoe you how to use it.