If your using 2 monitors, or have more then one window visible on your monitor and wish to take a screen shot of the active window, then give focus to that window you want to take screen shot of(click on it) then while holding the ALT key down press the Print button (maybe print screen on some keyboards). this will copy the active window to the clipboard which you can paste to a program like paint (Click Start, mouse over programs, accessories..Paint) c“lick on the white part of the window then while holding down the shift key press the inst key.
to save the screen shot click file save as , now you can save the shot to where ever you want, stanadard is to My Pictures folder. You should also select the format jpg in the drop down box, the stanadard bitmap that paint uses is very large, and not reconized by many photo programs.