One thing I am still confused about with hosting a server is the levels. Now, I have plenty of levels in the cache - maybe too many. How can I use those levels when hosting? How can you change the map you're playing on without taking down the server and setting it all up again? Any levels that I've downloaded, where are they saved and where do I need to put them so I can host them on a server?

Just basically tell me how to do this. I'm not sure. I already know I can host though. I've done it before. I just know I have more interesting levels to host than the ones that came with the game, but they don't appear to be there to choose from when I want to host a server. Help!