Cut out the floor of the house. Note that the three large tabs are reverse-folded. Score on the back of the paper and fold upwards. Fold the stairs down at a slight angle and the thin end of the porch down.
Push the stairs through the slot at the top of the porch support on the right side of the house, as indicated in the diagram. Glue the large tabs inside the walls and the front porch against the edges of the porch supports on each side of the house.