One Point Perspective Room

Here is the room complete with door and window! The same concept applies for both the door and window. You just have to know your lines and it isn't that hard.

One Point Perspective Room

Here is the simple one point perspective room with the guides (red). I just followed the directions and it was pretty easy to do and understand.
One thing I would like to mention is that it definitely helped me understand how to create real life 3D scenes that have depth to them.

One Point Perspective

Here is an example of one point perspective photography with a vanishing point. The horizon is shown in green. The natural lines of the photo leading to the vanishing point are shown in red. The vanishing point is shown in blue and seemed to be where the lines intersected.. The vertical lines are the rulers shown in light blue (I used the end of the bridge support beams and the end of the trees).