What populates the Webapi method\'s description on the helper page and the introduction paragraph?
To view the description you need to follow this :

In the Register method for HelpPageConfig class ( Areas/HelpPage/App_Start/HelpPageConfig.cs) uncomment the line 19 and don't forget to change the file path like this :
config.SetDocumentationProvider(new XmlDocumentationProvider(
HttpContext.Current.Server.MapPath("~/App_Data/MvcApplication4.XML"))
);
This all you must do. Last thing is to include the file created in App_Data in your project so the file will be deployed in production.