It's easy to take a screenshot:
  1. Press and hold the Power button (which switches the device on and off) and the Volume-down button (which regulates the device volume) together.
  2. In 1-2 seconds, you will hear a camera shutter which signifies that a screenshot has been successfully taken.
  3. After that, the system will automatically save it in folders /Pictures/Screenshots or /Pictures/ScreenCapture.
  4. Attach the screenshot to our conversation by pressing the Plus button in the bottom left corner of the screen.
P.S. If there is a Home button on your device, you will need to press and hold the Power and the Home buttons.