Hello, Keep in mind that for you to work on the floor and ceiling you need to actually see them. For the floors is easier, just select the Story you are working on from the Left hand pane, select the building option you want (floor) select the Style and color and then apply it to the floor section on the story you have brought up. Now, about the ceiling is a bit more complicated since to watch it you need to be inside the building you have build. By using the Camera controls at the lower left hand side you will be able to get in the building and look up to see the ceiling.
I do not understand what you mean by "when I place a fixture on any floor it goes to the basement" could you elaborate more on that?