Hacking Backgrounds on Windows
Big Business Client keeps a folder of textures for Backgrounds. Do not add your own.
If you find an image, such as by Googling, Where does Windows keep Wallpaper files, you can copy files into Big Business 14 Client's subfolder /Resources/BBIcons/texture/
However, if your image it too small to cover the screen or too large to load quickly or any number of other possible problems it could go badly and you should play it safe.
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