XNA 4.0 Adding surrounding Sphere/Box to the terrain

i have been searching开发者_如何学Python for long in order to find how i can place a sphere/cube around my playfield so ill have an effect similar to sky. I have seen SkySpheres/Boxes but couldnt implement them . Im looking for a rather simple solution since my play field is really small and i just need something to replace the Clear(Color.Black) .I dont care about collision i just need it to be there with a texture on . Thanks !

You should take a look at Riemers XNA Tutorial

HERE is the post on the skybox.