Hi Monks, I have no knowledge of perl, so please forgive.

My heartfelt advice to you is to fix that problem before going any further. Just as I'd not get into a car and drive cross country before I learned a) how to drive and b) how to navigate I don't suggest trying to do something as sophisticated as you're attempting without learning the basics first.

That said, let me lay out a foundation for you.

#!/usr/bin/perl -w 
################################################
# First line is called a "shebang" and on a *nix or Cygwin environment
+ loads the 
# interpreter
use strict;  # keep an eye on our code looking for major faults
use LWP::UserAgent;

my $res=authenticate();        # Call your sub.  You might want to  
                               # decide what to do with the return cod
+e.
# more code goes here
exit(0);

#the code you posted goes here
[download]

Find your self a book such as Learning Perl to get a handle on things. I wouldn't attempt to build a house without some basic construction technique knowledge.