To Paste an Image from the Clipboard
You can create new PNG files from images on the clipboard using the Paste command in the Edit menu.
Create a screenshot
To place a screenshot of the currently active window on the clipboard, press the Print Screen key while holding down the Alt key.
To copy the whole screen to the clipboard, press just the Print Screen key.
Copy images from other applications
You can also place images on the clipboard by using the Copy command in some applications. Once the image is on the clipboard, use the Paste command in the Edit menu of PNGOUTWin.