Lighttpd

On LINUX MINT ...where SYNAPTIC installed lighttpd......using the the bare minimum example conf file pointing to port 3000 and using 127.0.0.1:3000/cgi/test.pl
where the "cgi" directory is /home/rob/www/cgi/

The goal is to have a cgi PERL script that presents a data entry form ...plain HTML form.... that gets fields keyed in and then
submits a PERL script that takes those fields and writes an output text file.
THIS DOES WORK IF THE FILE IS ALREADY THERE
BUT
does not work to CREATE a new file.
WHERE
or HOW
do I define the permission to create files on the fly and not require them to already exist?

THIS IS NOT FOR PUBLIC access from the outside world.
It is strictly for local use on one PC.

 
server.modules = (
        "mod_access",
        "mod_alias",
        "mod_compress",
        "mod_redirect",
        "mod_cgi",
#       "mod_rewrite",
)

#server.document-root        = "/var/www/html" 
server.document-root        = "/home/rob/www" 
server.upload-dirs          = ( "/var/cache/lighttpd/uploads" )
server.errorlog             = "/var/log/lighttpd/error.log" 
server.pid-file             = "/var/run/lighttpd.pid" 
server.username             = "www-data" 
server.groupname            = "www-data" 
server.port                 = 3000

index-file.names            = ( "index.php", "index.html", "index.lighttpd.html" )
url.access-deny             = ( "~", ".inc" )
static-file.exclude-extensions = ( ".php", ".pl", ".fcgi" )

compress.cache-dir          = "/var/cache/lighttpd/compress/" 
compress.filetype           = ( "application/javascript", "text/css", "text/html", "text/plain" )

# default listening port for IPv6 falls back to the IPv4 port
# default listening port for IPv6 falls back to the IPv4 port
## Use ipv6 if available
#include_shell "/usr/share/lighttpd/use-ipv6.pl " + server.port
include_shell "/usr/share/lighttpd/create-mime.assign.pl" 
include_shell "/usr/share/lighttpd/include-conf-enabled.pl" 
##########################
  $HTTP["url"] =~ "/cgi/" {
      cgi.assign = ( ".pl" => "/usr/bin/perl" )
  }