In the Application Navigator,
Projects panel, projects are displayed as the top level in the hierarchy.
The Application Overview window opens by default in the editor window area when you create a new application. All objects that you create within JDeveloper appear in the Application Overview file summary pages, arranged by object type. You can create new files and artifacts, and view them filtered by status and project.
You can optionally close the window, since you will not be using it to create objects for this application.