You need to port forward, after that it already runs on your public ip, the server is automatically on port 25565 but you can change that in server.properties
When you press "O" it saves the world to the singleplayer menu, when you press "P" it saves it to a file. Currently there is no nice way to load files :(
you can make blocks walls and vice versa using the converter! craft it in the crafting table with Cobblestone in the corners Planks to the sides and one iron ingot in the middle
