About a Desktop Wallpaper on My Apple iMac Computer

I Don't know if i should post this here not sure? but sorry it's in the wrong forum if it is? so here i go here is what i need help with --> I Have a Desktop Wallpaper of Mandy Moore but this Wallpaper can't be found on the internet & I Have an Application from Apple Mac App Store it's Called Snapheal Mac App so i'm trying to Fix this Desktop Wallpaper to go just right without the toolbar on top but in Snapheal Mac App i'm having a problem trying to get it to go perfect so i need help, so if anyone on here has The Mac App Snapheal from Apple Mac App Store is it ok if you can help me out on fixing this Mandy Moore Desktop Wallpaper so the Toolbar on Top is gone? cause i don't know how to get it perfect, it keeps messing up on me for some reason? & there is to many settings that i'm gonna do trying to get it to go perfect & i don't use this App oftan & i have a 24inch Apple Widescreen iMac Computer so i need it the right kind of size as a desktop wallpaper to fit my screen & it has to be JPG Format, can anyone help me out?

here is the Wallpaper