To capture a screenshot of the entire screen on a Windows 7 PC, first press the Print Screen button. Next, go to Start, click All Programs, click Accessories, and then click Paint. Once the Paint program opens, navigate to the Home tab, go to the Clipboard group, and click Paste.
If you want to resize the image, navigate to the Home tab, go to the Image group, click Resize and enter a new pixel size or percentage. Once you're done editing the image, click the Paint button, and click Save. If you only want to capture an active window, press Alt and the Print Screen at the initial stage, instead of Print Screen alone.