The cheap and easy way? Freeze frame the screen you want (there's a speed slider up by the top). Hit "PrntScrn".
Right click on your desktop, go to New, then "Bitmap Image" then give it any name. Open the image, and hit "Ctrl V" or the paste icon. Then move the image so that the edges crop out the "junk" and you only have the screenshot that you want.
It's easy (sort of), it's simple, and all it takes is MS Paint.