creating slide fr you tube video/where is the print screen on Thin

I'm told that I can pause the video, push Alt + Print Screen, and that the
image will be stored to Windows Clipboard. Maybe that happens, but I see
nothing, and I can't figure out how to access the Clipboard. Have read a
billion pages of instructions from Dell and MS, but to no avail. Very
fatigued - help would be appreciated. (I'm working on niece's dell desktop
because my Lenovo ThinkPad T60p doesn't have a Print Screen button - read a
lot of Lenovo stuff to find out what an alternative function button would be
(or anykind of keyboard button), but couldn't find anything. If any
--
Techno-peasant