Just fly your ships right to the center, and if you researched the tech they'll jump right through
Your ships should simply utilize the wormholes in a shortest-route method - for instance, if "planets" x and y are wormholes, and you have a ship in x, clicking somewhere in y will cause your ship to travel through the wormhole.
When I select fleet and right-click wormhole, I get not "colonizable planet" or something to that affect. Question: if you on a map with multiple wormholes how do you determine which one is the exit hole (planet x)?