Once you've learned how to create areas, the next step — if you're so inclined — is to learn to program Wyvern. Programming opens up new vistas that aren't possible using the standard Wizard tools.
The first subtab above, Overview, walks you quickly through the entire development cycle from the viewpoint of a programmer.
The Tutorials subtab contains many hands-on mini-tutorials that show you how to accomplish various programming tasks in Wyvern: making new commands, creating guilds, manipulating monsters and objects, and so on. You'll find lots of code and even more explanations.
The Examples section is more of a reference. It has lots of code, but not much explanation other than in the comments. Once you've been through all the tutorials and you've practiced writing your own code, the Examples should be helpful in showing you even more things you can do. Feel free to suggest new examples to add to this section — all of them come from the actual game.
Sometimes your code just doesn't work the way you were expecting. That's where the Debugging Guide comes in handy. It's a lengthy tutorial on adding logging to your code, so you can see what's going on inside it when it runs.
The API Docs subtab takes you away from this manual, to the auto-generated javadoc documentation for the Wyvern Game APIs. It lets you browse all the thousands of classes and methods available to your code.
The subtab is for highly experienced programmers who wish to try their hand at creating a new game client for Wyvern. It's for experts only.