How to take a screenshot on a Mac: Shift-Command-3 for whole screen or 4 if you want to select
The pointer changes to a crosshair.
Move the crosshair to where you want to start the screenshot, then drag to select an area.
When you've selected the area you want, release your mouse or trackpad button. To cancel, press the Esc (Escape) key before you release the button.
Find the screenshot as a .png file on your desktop.