Now that you have your server set up, you're going to need to control it. Fortunately, OS X Server can be controlled in a number of ways, both using the server or using another computer.
Using Server.app on Your Server
The first way that you can control your server is simply by using the Server app that you installed already. Simply launch Server, select "This Mac" from the list and log in with an administrator account. Now, you have access to the full array of server controls for all of the built-in services.