1. Check your screen size, e.g., 1024x768 or other.
   (for Windows, right click on a blank part of  the desktop and select "Properties" >>> "Settings" (tab))

2. (in Poser) ... Render to your screen size, e.g., 1024x768 or other, and save the image.

3. Load your image and set your wallpaper to be "centered."

And ... that should do it.

cheers,
dr geep
;=]

Remember ... "With Poser, all things are possible, and poseable!"

cheers,

dr geep ... :o]

edited 10/5/2019