1 Point Perspective: There is a horizin line shown on the top of the screen and then you place a point called the Vanishing Point on the right to make all the depth lines look the same and they all go to that 1 vanishing point.
I plotted the vanishing point on the top right on the horizon lineand then I created the box based of the vanishing point where I drew the depth lines towards the vanishing point. This was difficult at first but once you get used to how the lines work, were each one goes, what lines do you need to draw in order to help. Like you might draw a line to the vanishing point that can help you out with something else to draw.
This was difficult, but if you challenge yourself enough and try alot of them you can get used to it where the depth line lines up with the vanishing point and where the circles/semi circles and what lines from points need to go to the vanishing point in order to measure/draw other things that you need.