Hey pmack,
When you go to the pro shop on your iPad, toward the top right you will see a "coin gear" category where you can rent equipment using those silver coins. But looking at your current equipment there is nothing in the coin gear that will interest you. I'm hoping WGT will, at some point, allow us to use coins to purchase balls or come up with some kind of trade for credits, but I'm not holding my breath.
Cheers,
Mick