hey guys thanks for eading so i have 2 monitors inyto 1 graphic card and their both running fine how can i have league of legends or another game run in both moniors at same time instead of 1?
It won't work with competative games like LOL, otherwise having 2 monitors would give you a better FoV and give you an unfair advantage. In a game that isn't limited however you do in to the cards control panel and set up either surround (Nvidia) or EyeFinity (AMD). Once that's setup you can simply change your resolution in game to the one created with surround or eyefinity.
also how can i stretch or use a desktop backround to cover both monitors
not sure about stretchig unles you just put it into photoshop and stretch and crop making 2 backgrounds - i dont know any other way :/
You can never use 2 or more monitors as a single monitor unless you configure it as such in your Nvidia or AMD control panel (Surround/Eyefinity). By default when you plug in multiple monitors you only get the options to mirror the displays or have each additional monitor as an "extended" display, meaning each monitor is independent of each other.
Regarding the wallpaper question, in Windows 7 or prior you cannot stretch a wallpaper across multiple displays (The workaround is to use Nvidia/AMD Surround/Eyefinity to make your multiple monitors a "single" monitor then set your wallpaper as usual.) Now, Windows 8 natively supports spanning a wallpaper across multiple extended/independent displays. Just go to Desktop, right-click -> "Personalize" -> "Desktop Background" -> Choose your wallpaper then in "Picture position" choose "Span".