

(First drawing is what I need help with, the 2nd one is my rendering style)
Hi, so ive been drawing for over a decade, Ive never really gotten the hang of shading and rendering until recently. Ive made three really good pieces where im incredibly proud of the shading and rendering but I took a break shortly after due to burn out and now ive lost all of my progress. Im currently trying to shade and render the piece above but I literally cant find out where to place the shadows, It's like ive completely forgotten the form of the body and how it reacts to light. I also cant for the life of me figure out how to render the skin and clothes, all I have is a basic sketch and its taken me over 20 hours bc I keep restarting my shading process. Can someone either show or describe where to place the shadows, or possibly give me tips on how to render the two people in the drawing?