what i recommend, since the problems i usually have, since i don't have photoshop, and this is a weird format, i must put it into paint to save it into something people can use.
So i would just save the picture. Then manually set your wallpaper
Start>my computer?change a setting/control panel>display>desktop/wallpaper>find the name>strech, apply
Just incase you don't know, but you should i think

Either way, i think it's cool at least, could be better if i had photoshop and didn't have to worry about the lose of detail from saving it in paint, but o well.
Ok for people asking, the eyes are just there, i mean the thing is nightfall... kinda creepy right? Well arn't those eyes creepy?