When you are drawing in perspective, you need to figure out how far apart certain lines need to be. If you are drawing something that occurs in a pattern, like telephone poles, the objects get smaller and closer spaced the farther away it gets.
This website just talks about the lines, and steps you need to place on the paper to complete your drawing. The factors that applies every time you are drawing this way are vanishing points, and a horizon line. You need both of these factors to draw realistically.