Hi operating, and welcome to this forum!
I may be wrong, but I think there is no screenshot function within the game.
At least i do my by pressing the print key on my keyboard, next thing is to Tab-out of the game and paste the captured screen into paint shop, and from there i save it.
To uploads i use photobucket.com.
Btw.:
while you wait for your game, you might want to read this forum thread:
Information for new players