If you're the guy who had this question answered on IRC earlier, ignore this. (:
Else, it can be found by clicking on your CP amount under your character picture on the right menu, then selecting the [Exchange CPs] link from the top of that page.
Remember that you must be on the surface of a planet, not inside any rooms/ships/facilities to exchange for ships/vehicles. You can exchange for credits at any time, anywhere, but the rate is fairly low and will probably not be worth it.