Hello and welcome to Tom's Hardware Forums.
First off, it's best to edit your e-mail address out of all four of your posts (by the way, one would have been enough) before it's captured by the Spam bots which trawl the net for addresses to abuse.
You find the desktop wallpaper setting by right clicking the desktop and going into Properties then click the Desktop tab. The list of Windows wallpapers is there but if you have a personal photograph, click on the Browse for that.
If you have a problem with your own photograph, copy it and paste it into C:\Windows\Web\Wallpaper and it wlil be added to that list of Windows wallpapers.