When the GWT support is enabled, you can start developing GWT application components.
The standard GWT package layout facilitates differentiating the client-side code from the server-side code. The image below illustrates the structure of a standard GWT package.
Individual units of a GWT configuration are XML files called modules. A module bundles all the configuration settings that your GWT project needs, namely:
The GWT Module XML descriptor (5) should reside in the root package of a standard project layout. IntelliJ IDEA can simply generate a GWT Module with the corresponding project structure for you.
A module entry-point is any class that is assignable to EntryPoint and that can be constructed without parameters. When a module is loaded, every entry point class is instantiated and its EntryPoint.onModuleLoad() method is called.
To get more familiar with the GWT application structure, have IntelliJ IDEA generate a GWT Sample Application for you.