Gather these parts first. 

Glue the hook rails in so that the hooks are pointing down toward the edge of the back that is flat.

Glue the reinforcement plates around the back of the hook rails as shown.  make sure that the corners of these plates match with the corners of the back plate.

Gather these parts

Glue the front onto the sides as shown. Make sure the detail is all facing out.

Glue the top in place as shown.

Glue the assembled back-plate from the beginning onto the shell from the previous step with the hooks on the outside.