Let's say you only have three points: A, B, and C.
The first step is asking you to construct a parallel of AB through C. You should start by placing a ruler connecting points A and B, then use a set square and rest it on the ruler that's connecting points A and B. Slide the set square over the ruler so it meets point C. Measure at which distance is point C. Then slide the set square to one or another side of the ruler and mark a new point with the same distance of point C from AB. Now connect points C and the new one by tracing a line that passes on both points. That line will be parallel to AB.
Now repeat the process for the other parallels. By the end, you should have three lines that when extend cross each other and form a triangle.
