You need to cut the steel bar that joins the glass knobs in half. A little tricky but you just need the right saw and make sure you wear eye protection.
Measure where you want the knobs on the board. Spread them out evenly and then drill your holes into the wood, make sure the drill bit is NOT to big, the steel rod will have to fit very tight, or the knob will fall out.
I then attached the circular back plates to the board, you would not have to add these but it gives it more charm.