Taking a screenshot with iOS devices is very simple. Android 4.1 includes a built-in way to accomplish the same thing on Android smartphones and tablets.
To take screens on the Google Nexus 7 tablet, all you have to do is go to press the Power and Volume Down buttons at the same time and hold. It's easy to press together using one hand.
Then pull down your notification tray, touch "share" under the screenshot, choose the service you want to use.