Gather these parts

Glue hook rails into the sides of the back plate so that the hooks are pointing down

Glue the detail plate on top of the backer as shown. The bottom of the detail plate should line up with the top and bottom of the plate

Glue handles into the slots at the bottom of the roll-up door

Glue the door frame on top of the door with the bottom lines up with the bottom of the previous assembly as shown

Glue light fixture center into the slot above the door

Glue light fixture ring around the light center