There are various "screen grab" programs available, but I just use the Windows screen capture method.
To capture the entire screen image, press the "Prt Scr" Print Screen button.
To capture the image of a single window, hold down the "Alt" key and press the "Prt Scr" button.
This will place the screen capture image into your copy & paste buffer. Open a program, such as Paint, and paste the image. You may then edit the image as desired.
Some mobile PCs that don't have the Print Screen button might use other keyboard combinations, such as Fn+Ins, to take a screen capture. Check the information that came with your computer or the manufacturer's website for more information if your keyboard has no Prt Scr button.