Are 당신 on a Mac? If so, press the "Command","Shift" and "3" keys simultaneously to take a picture of your entire screen. To take a selective picture, press "Command", "Shift" and "4" and select the area 당신 want to take a picture of. Your pictures will automatically be saved on your desktop.
Ok so on the 상단, 맨 위로 of your keyboard right of the F12 button there should be a key that says "PRTSC SYSRQ". Press that then go to paint and do CTRL V, save and ta da! :)
당신 can also use special software for taking screenshots - Jet Screenshot, for example. And if 당신 use 구글 Chrome I'd recommend Awesome Screenshot add-on for capturing whole web pages 또는 their specific areas.