To take a screenshot on the Samsung Galaxy S7, simultaneously press both the power button (found on the top right) and the home button (found on the bottom center of your device). A shutter sound as a quick flash on the screen will let you know the screenshot has been successfully taken. Screenshots are by default saved in the Gallery app or your Google Photos.
Learn more about the capabilities of your Samsung S7 or the 150+ other features Blue Mail has to offer.