Gus65 - you will need to learn how to post images on the forum if you are to get reasonably quick responses - I'd keep trying, its worth it.

On your original problem, I would say that the 'normal's are what is confusing you. In 3D games, the graphics are rendered as triangles. The tricky thing is, they are rendered as one-sided triangles almost always. So the normal refers to which side of the triangle is actually rendered (shown).

What you are seeing, with the outside walls not showing, is the back-side of the wall closest to you, so it is invisible, and the other walls show through - because you see their "front" side.

To "fix" this if you have to, make the walls around your room a full wall - so each side of the room is a cube stretched out to the shape of the full wall. This way you have a wall (2 triangles) with normal facing inside the room, and a wall (2 triangles) facing out of that room, and visible from any neighbouring room, or outdoors area.

Hope that helps,

Don
have a great day