[plt-scheme] newbie: web server tutorial questions

http://docs.plt-scheme.org/continue/index.html

On that note.  I'm having trouble:
regarding the end of: http://docs.plt-scheme.org/continue/index.html,
just before the https section,

I did:
> mzscheme -t blog.ss
blog.ss:150:33: compile: unbound identifier in module in: path

sooooooo, is <file.ss> supposed to be the same value as
"APPLICATION.ss", and are both of these supposed to be the place the
application code was getting cut and past?  Are all the ss files
supposed to reside in a servlets folder?  and is

        #:servlet-path "/servlets/APPLICATION.ss"

a relative path to htdocs?

and in

       (list (build-path path "htdocs"))

is htdocs relative to where you run the mzscheme command?

Thanks.