I need some help in cinema.

My problrm is that always when i am trying to render some image i have done, i have black beck ground! how can i switch the beckground color?
look at the image:
http://planet.nana.co.il/buildal/render%2Ejpg
there is no way to switch the beck ground.

Insert background object (Object-Scene-Background).
Make material with whatever color you like.
Apply material to the background.
Shift+R

Greetings: HeroShirt

Thanks.