The snipping tool is the easiest way to get a piece of a screen. Use the search box to find "snipping tool".
The PrintScreen button on the keyboard takes a picture of the entire screen.
ALT+PrintScreen takes a picture of just the active window. Paste in Paint to edit and save.
Command+Shift+4 gives you cross hairs to drag to capture a piece of the screen. When you release the picture is saved to the desktop.
Screen Shots