Volumetric lighting in cycles?

There are too volume shaders in blender, volume absorption and volume scatter, combine the 2 for a full shader and you can make all kinds of fogs mists and nebula.

Thanks for reply. I created a shader with a mix shader and the two connected to it. Added this material to a plane, but the colour stays black. Watched a tutorial, and there it was attached to the world otput, but I already have a sky background...

So where is the shader added ?

Thanks

You have to add the volume to a mesh you create in the scene where you want the foggy effects to exist. like here where i added the shaders to a box, and you can see how the light fades as it penetrates the mesh.

So here is the render without volumetric light. I want the volumetric light come throgh the windows, so basically everywhere. 

But the shader still looks black...

Thanks

ah I forgot to put it on volume ;) thanks a lot