The easiest way to take a screenshot is to press "Applications", "Accessories" and "Take Screenshot".
I think that this function is useful when I need to illustrate an idea. For example, I can show you how to use a software item.
I can get the screenshot of the whole Desktop area. I can also select a part of this area or select the current window in use. I can also specify the number of seconds necessary before taking a screenshot. This delay is important when I need to capture the image after clicking on more than one button.