Here are 2 methods to take a screenshot on this device:
1. Go to the screen that you want to capture.
2. Press and hold the power button+volume down button for few seconds.
3. A sound will be heard or you will get a notification that tells you that your image is captured and is saved in your gallery.
1. Go to the notification area and you will find a screen shot icon.
2. Open the screen which you want to capture and click on that screen shot icon. Your screenshot image will be saved in your gallery.
I hope this was useful for you.