When you make a mistake like this you need to 'stop thinking GUI' and get to the command line:
(1) What is the user ID your web server runs when users are connecting? Hint:
Code:
ps aux | grep httpd
(2) Does this user ID have executable permissions for the
PERL or other CGI scripts?
(3) Does this user ID have read permissions into the HTTP document tree?
These are the things that the author of your cryptic note were trying to point out, and when you have these types of problems, you must 'leave your GUI' on the sidelines and learn to navigate the shell and use basic shell commands like
cd, ls, pwd, find, chmod, chown, ps, grep, more and do some snooping around the fun and friendly filesystem.
FWIW: In over 15 years of UNIX and Linux work, I've never used a tool like Webmin.... it is just too much fun and a lot faster (when you get used to it) to command the shell !!