The Diagram view provides a visual representation of the Web project. Here, you can create packages, folders, and web resources.
For editing the sources, the approptiate editors can be directly opened from the Diagram view. For example, by double-clicking a JSP page, the JSP editor is opened.
The Web project exists. See Creating Web Projects.
In the J2EE Explorer or J2EE DC Explorer, select the Web project (alternatively, select the relevant folder or package in the Web project) and choose Open Package Diagram from the context menu.
See also:
Creating Folders in the Diagram View
Creating Packages in the Diagram View.
Creating JSP and HTML Pages in the Diagram View
Importing Resources in the Diagram View