You'll be able to select the area you'll capture when you'll press that key. Selected area, fullscreen or the active window.
Afterwards, you'll be able to edit it thanks to some basic photo edition tools included. Add text boxes or draw anything on it thanks to the pencil. It's up to you.
Finally you can choose where you'll store the screenshots taken: send them by email, store them in your HD or upload them to your FTP.
It's a free and good choice if you want to try a new screen captor.