There are 2 ways to capture an image from your desktop using Windows Functions.

The first is a Screenshot:

Press the Windows key and the Print Screen key to take the screenshot, and the screenshot should default to the Pictures folder on your computer. The Screen shot will capture the image of what you're seeing on the monitor when you do it. (the image will include all monitors you have, not just the one with your active program and cursor)

The Second is the Snip and Sketch

Snip and Sketch can be found by typing "Snipping Tool"  into the Windows search bar, or going through the Start menu, to the Program, and down to Snip and Sketch. This will let you draw a box around the area you want to capture and then draw on it as well.