There are a few things you need to take a screenshot of one monitor. The first is the monitor itself- this is the screen that you will be screenshotting. The second is your computer, which you will need to be in Windows or MacOS. The third is the software that will be used to take the screenshot- most commonly this is Windows Paint or Mac Paint. Once everything has been set up, just click on the “Take Screenshot” button and your screenshot will be taken!