Material Properties for Objects in the Scene

Hi,
I have drawn a room.In the room
i have to put a conical light source that
projects the light onto a painting on the wall…i was wandering if someone could assist me in understanding how to put material properties to the walls,ceilings, and the floor so that it gives 3D effect. Also how would i make a light source to come out of a cone…
i really appreciate for the assistance
thanx