Attach one upper rail, one piece post and another one piece post using two Allen bolts. Repeat for the other side.
Attach one bottom rail to the post using one Allen bolt. Attach the upper rail, two posts and the bottom rail to create the first frame.
Attach another bottom rail to the post using Allen bolts. Attach another upper rail and two posts to create the second frame.
Lay the two frames down on a soft surface. Attach both frames using a horizontal rail and a back rail. Fix two pieces of slant rail on the sides using Allen bolts. Attach the top rail to the horizontal rail using Allen bolts.
Lift the playhouse so that both legs are upright and the roof is on top.