I found out that I could take screenshot and save them as image just by holding windows key and pressing print screen key. I would like to do this without having to press windows key. Which means that every time I press print screen key, it should capture the screen and save as image automatically as it would when I press and hold windows and press print screen. OR any single key press.
It depends on how general you wish that behavior to be. If you wish it only when running a particular software package, there may be an option within that piece of software. If you wish this to happen always, you must convert the signal send by the print screen key to the same signal sent by the windows + print screen combination. There exists various key mapping software packages with various capabilities.
I use a software product called "Greenshot" specifically designed for screen capture. It is invoked by the single print screen key. Green shot then allows the capture of an arbitrary region of the screen. The image can be sent to a printer, a file, the windows clipboard, e-mail, or an image editor. It is free, open source software. It installs easily and works like a champ.