I am a C++/C# developer and never spent time working on web pages. I would like to put text (randomly and diagonally perhaps) in large letters across the background of some pag
If you add "background-attachment: fixed" to the css in kavendek's suggestion above, you can "pin" the background image to the specified location in the window. That way, the watermark will always remain visible no matter where the user scrolls on the page.
Personally, I find fixed background images to be visually annoying, but I've heard site-owners say they love knowing that their logo or copyright notice (rendered as an image, presumably) is always right under the user's nose.