How to take a Screenshot on your Mac
To take a screenshot of a portion of your screen and save the png file to your desktop press Command Control Shift 4, then select the portion of the screen. Navigate to your desktop and you’ll find a file called Screen Shot [date].png
To take a screenshot of a portion of your screen and save the png file to the clipboard press Command Shift 4, then select the portion of the screen. Navigate to Mail or a document and press Command V to past the file into Mail or the document.
Also see https://support.apple.com/en-ca/HT201361












