Once you have it, you then run editing functions to make it better for what you need.
You will use the mouse to drag it to the areas which you wish to capture.
You are at liberty to choose what to take if it is the entire window or a specific part. If you want to have some video tutorials for a training then it is the most efficient application for this purpose. It helps to achieve this as snapshots as well as record videos. All you need is a special tool like the SnagIt. Of course, this is not possible with the webcams or even the screenshots o the pint key on your keyboard. You may need a reference to all the desktop activities. Windows has a default printscreen key and screen capture tool but often you need a more adbanced one that is capable to edit and share the images.