when the image that you want to copy is on the screen click shift+print screen (the left button in the set of 3 buttons along the top of the keyboard to the right of the F# keys). then open a program like paint (or photoshop if you have it), select new, and then hit control+v to paste the copied screenshot. then you can crop out just the part you want using the select tool, cut, and paste into a new document.
hopefully that makes sense.
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"to be nobody but yourself in a world which is doing its night and day to make you everybody else, means to fight the hardest battle which any human being can fight, and never stop trying." - ee cummings