If you are wanting the look of the tabs across the top - I have sewn them under the binding at the back and then wrap to the front, anchoring with a decorative button. As to spacing - I use pieces of paper laid under the hanging as it lays on a table to experiment with size, distance between, number of tabs etc.
If you don't want to anchor to the front then sew on with the binding, laying them on the front surface and wrap to the back and anchor after you finish the binding.