All I do is hit the "press screen/sysrq" button (beside f12) then go into my start menu and click on "accesories" then click on "paint", then click on the "edit" at the top left hand of screen, then "enter name of shot" then click "save as jpeg" and thats it...
It then goes into your picture folder...you then add it as an attachment in your post, then click on browse and then click on your pic/screenshot and hit submit..
Hope I didnt confuse you...but it really is easier than it seems...if I can do it trust me anyone can