How can I get a development card and then use it?
Left click and hold your mouse cursor on the catan board and drag up so you can look below the board, then, if you have a Wheat, Sheep and Ore click the question mark grey cards on the right side. To use it you then need to wait till next round and double click the Development Card that is displayed together with your resource cards untill it comes out of the deck on its own in the middle of the screen, it will then have a "check" symbol next to it in order to use it.
This does not work for me. I can't figure out how to purchase a Development Card. Clicking on the "?" deck does nothing, even if I have the resources.