This issue occurs on the page at http://docs.oracle.com/javaee/6/tutorial/doc/bnaeo.html. There are several sections describing how to add error pages, context parameters, and initialization parameters. However, all of those talk in generalities instead of specifying sequences of steps that can be taken with the hello2 project to see the results.
As an example, I'd suggest including an error page in the project that isn't hooked up, and include an error that triggers it. The task sequence hooks up the error page, and the user can see the effect of the actions.