I tested the last part of tutorial ("More advanced again - Make a webapp around the service"), which I found clear and straightforward. However I did run into some trouble with the following piece of code.
(defconst my-elnode-editor-urls '(("^/text/$" . my-elnode-editor-handler) ("^/update/.*$" . my-elnode-editor-update-handler) ("^/[^/]+/.*$" . my-elnode-editor-webserver-handler)))
The last line I had to change to: ("^/.*$" . my-elnode-editor-webserver-handler)))
to be able to access http://localhost:8002/my-elnode-editor.html