Yes, you need to do that with putty. It might be easiest if you change to the "pictures" directory first, then you can simply grab and view the screenshot.png via the "Pictures" share on your PC:
Then repeat the hyperion-dispmanx (just press "cursor-up" to recall it, then return) while you view different pictures on your RPi and check the screenshot.png on your PC.
While you're at it it would be good to grab some info about your system. Please run the following commands and post the URLs: