Hi Terry, it may be helpful to understand one point, two point and three point perspective. This link explains it well I think.
http://www.watercolorpainting.com/perspective_1_2_3_point.htm
As an exercise, you can sketch a railroad track. Then try sketching one at an angle. Then try making it a railroad that's on a bridge with pylons over water. Another good way to grasp it would be to draw simple cubes like we did as kids....a square with a smaller square inside that you connect the corners on. If you extend those lines out on the cube until they intersect then you will see your perspective point.
http://www.watercolorpainting.com/perspective_1_2_3_point.htm
As an exercise, you can sketch a railroad track. Then try sketching one at an angle. Then try making it a railroad that's on a bridge with pylons over water. Another good way to grasp it would be to draw simple cubes like we did as kids....a square with a smaller square inside that you connect the corners on. If you extend those lines out on the cube until they intersect then you will see your perspective point.
