putting a frozzed picture

I’d like to draw a picture that move with the screen on the scene like we can see in Starcraft for example, a piece of
the screen where you can choose an house …
Someone can help me ? I have heard of stencil buffer,is it a solution ?

I think what you need is whats called an ‘isometric’ engine. There are a lot of things about this kind of engine on gamedev.net, perhaps flipcode.com as well.

About the stencil buffer…maybe you should read a bit more about what that thing is. The redbook is a great place for that.