you need to put the back on when you make the (sandwich)- as in top, batting, backing---then add your buttons---like a tied quilt---they would substitute for quilting-then binding.
the fusable batting is fusable on both sides- adheres to top & backing- binding is the last step.
and from the picture it sure doesn't look square- but that is probably from the angle of the picture- it looks as if it is 9 or 10 across & the same top to bottom- so that would make it pretty square. very cute! i love the fabrics.