Do you know?
you can capture entire screen only by your keyboard without any third party software.
Have a look at your key board.
There is key looking with the label "PrtScn/SysRq" (Print Screen/System Request).
When You Click on this key - Whatever on the screen will be captured and stored in the clip board.
Then you open any image viewer software -> click on edit many and then click on paste option.
Or
Open Windows utility Paint
and paste it.
Screen capture will be paste on this utility.