In your LogonStudio folder,(mine is C:\Program Files\Stardock\Object Desktop\LogonStudio) look for a folder that contains your theme.
Copy that entire folder to the same location on the desktop pc.
This is assuming of course that you have installed LogonStudio to your desktop pc.
Now, if you are wanting the background from a logon to be a wallpaper that is something different.
In the above referenced folder (the one that contains the theme), the background is usually called Bitmap_100.bmp. I think you can take it from there.
By the way... good to see you hangin around again Denny!