If your on mobile, you press the power button and home button/ swipe up (if you have a new phone) to screenshot, other wise if you’re on a computer, then idek sorry
“ Mac. Hit the Command, Shift and 3 keys together to take a screenshot of the entire screen: When using Mac, pressing the Command, Shift and 3 buttons together will take a screenshot of your entire screen. This screenshot will be automatically saved to your desktop.”
-Google