Hi Mehdi, looking good! :) For the retopo, you should first decide the polygon budget your aiming to. This depends on what you want to practice on. So for example a big console game can go as high as 300k per "hero" character (with hair cards and high definition faces) while a mobile/esport will be much more conservative…
I am making a shipping container and on the doors there is a shading or normal problem, I checked the number of edges for each face and they're all 4 edges, any suggestion?