After PrintScreen Now is installed on your computer, you should see its icon in the Windows system tray (also known as the Notification Area) located next to the system clock. If you do not see this icon, the PrintScreen Now program probably isn't installed on your computer.
If you suspect that some of the icons from other programs are also missing, they may have been hidden. Please see this helpful article from MyDigitalLife for information on how to unhide the icons.

Windows system tray

Whenever you want to print your screen, press the PrtScn key on your keyboard. If you use a laptop/notebook computer or a desktop with a mini keyboard, your PrtScn key might need to be used with a separate Fn key. If that is the case, you must press both the Fn key and the PrtScn key at the same time.

Standard full-size keyboard Laptop/mini keyboard

Then you'll see the familiar printer dialog where you can choose any of your available printers. Select your printer and click Print.