Gather these parts.  They will form the core of one block of lockers.

Glue the front and back plate into the sides.  Make sure that the Details on the back are facing out and the pegs are all facing up.

Glue the top plate onto the pegs on top.

Gather 4 of these locker dividers.

Gather 5 locker doors

Glue the dividers into the slots on the front of the block and then the doors in between them.