To set the marble as wallpaper on your desktop:
(Attention, Microsoft: this makes no sense...who has wallpaper on their
desktop unless they're a wallpaper hanger?)
Click on name of marble sample to view large, downloadable version of marble type of your choice. With cursor over any part of marble image, right-mouse button click and select "Set As Wallpaper". The marble should show up on your desktop. To change, or delete your desktop wall paper, go to Settings--Control Panel--Display--Background.

If You Want the Tile, But Haven't Built the Bathroom Yet. . .
With cursor over any part of marble image, right-mouse button click and select "Save Picture As . . ." A dialog box will appear prompting you for a location to save the Picture and whether you want to save it as a .jpeg or .bmp. Usually you will save it as a .bmp file if you want to use it for wallpaper. To find the default location for wallpaper, just go to: Settings--Control Panel--Display--Background and click on "Browse". The browse dialog should open to the location of all the other .bmp files that are stored for wallpaper.