Begin by launching the Server Launcher.
Starting a server with a world that was previously saved can be done from the Select Saved World button.
You can choose a world from a list of your saved worlds. After selecting a desired world click Start Server with Selected Saved World button and your server will start.
An easy and convenient way to transfer saved worlds from one computer or another is to export the world to a zip file. This will contain the many smaller files needed to transfer all of the needed player data and world information in to a simple package.
Connect to your server
Once your server has started, you will see the details about your specific world. Be sure to write down the ip address of the server so that others may connect with you. If you need to modify any of the player or world properties, you can do that from the server window or in-game with the teacher menu.
By pressing the World Information button, you can set some final settings for your world, such as the Message of the Day, and Welcome Message for users as they connect. This screen also tells you some basic information about your world.
Always remember to either save or back up your work before taking down the server!