To screen capture you press the "Print Screen" key (usually upper right on your keyboard, one of those keys). Now load any graphics program (Microsoft Paint is fine ...), press paste.... it'll paste the screenshot. Now save it as a jpeg.
I finally had to add the advertisement blocking plugin to Chrome. Now I have no advertisements on this site.
To do this download Google Chrome, then search for adblock chrome and follow the instructions. By default the Samsung advertisement will be gone, along with the main ads. The buttons you have to remove separately if you want, but it is quick and painless.