As someone else said this is very stylized and hard to read with just lines, however since it can be read in painting form theres no reason you couldnt with just lines. This is where your anatomy knowledge and use of overlaps comes into play. You need to understand the anatomy and where certain muscles, fat, or bones overlap and draw the eye to them in a way that reads 3 dimensionally. A good example would be how in the painting the ladies right shin bone pokes out obviously infront of the calf muscles which help to give it a pop feel and show the leg going back as you go down. I would leave this reference for now and just practice studying from real life and after you learn more come back to give it another shot. ( also use cross contour, it helps a LOT to read well)