guest world is not ment to be a permanent place for people to live, its meant for guests to gather resources while their app is being processed. being a member means your app was accepted, and you can build and talk in the main world. starting a town is simple really, find a nice size area of unprotected land thats a way form any other regions and towns, and start to build your town. once you have some plots/houses built, mark off the area in a square/rectangle with something that clearly defines the area. after that, type in your chat bar /pe new can i please have this area made into a town named <whatever here>. also view
This Link for the MT wiki, which is full of valuble information which will help you in managing your town. you can also view
This Thread for a rundown on how to set up and manage your city.