Create the special_pages/ directory in your tutorial catalog directory (not in the pages/ directory).
As mentioned, it is a good idea to display an error page when Interchange is asked for an unknown page. To create a missing page for display, type the following and save it as special_pages/missing.html.
[include top] [include left] <p>We're sorry, the page you requested has not been found.</p> <p>Try finding what you need on the [page index]welcome page</a>.</p> [include bottom]
The addition of this page ensures that users see your error message instead of a mysterious server error if they mistype a URL.