It's basically an NFG (non-faction group). Players take the initiative to organize themselves around some cause they deem worthwhile. If you have something in mind and don't really know what resources might be useful or if you just want to gauge interest, you could open a post on the forums about it to discuss it with the rest of the community. The General Talk forum would probably be a good starting point. SWC has no features that support this, though, and it is solely an independent effort. But if you are looking to create a society around a specific race or homeworld, you may also want to look up the homeworld or planet on the galaxy rules to determine which faction governs it, as they may be willing to help you out a bit, depending on your plan.