what is the problem in this script and why it makes error

#! /opt/lampp/bin/perl -w
#@ MAIN_LOGIC
# todo1.pl - initial version of to-do application
 
use strict;
#use lib qw(/opt/lampp/bin/perl);
use CGI qw(:standard);
#use WebDB;
 
print header (),
	start_html (-title => "To-Do List", -bgcolor => "white"),
	h2 ("To-Do List");
 
# Dispatch to proper action based on user selection
 
my $choice = lc (param ("choice"));	# get choice, lowercased
 
if ($choice eq "")					# initial script invocation
{
	display_entry_form ();
}
elsif ($choice eq "submit")
{
	insert_item (param ("content"));
	display_entry_form ();
}
else
{
	print p ("Logic error, unknown choice: $choice");
}
 
print end_html ();
#@ MAIN_LOGIC
 
exit (0);
 
# ----------------------------------------------------------------------
 
# Insert new to-do item if the content is non-empty.
 
#@ INSERT_ITEM
sub insert_item
{
my $content = shift;
my $dbh;
 
	$content =~ s/^\s+//;	# strip leading whitespace
	$content =~ s/\s+$//;	# strip trailing whitespace
	if ($content ne "")		# if content is non-empty, add to table
	{
		$dbh = WebDB::connect ();
		$dbh->do (qq{
			INSERT INTO todo SET t = NOW(), status = 'open', content = ?
				}, undef, $content);
		$dbh->disconnect ();
	}
}
#@ INSERT_ITEM
 
# Display entry form
 
#@ DISPLAY_ENTRY_FORM
sub display_entry_form
{
	print start_form (-action => url ()),
		"To-do item:", br (),
		textarea (-name => "content",
					-value => "",
					-override => 1,
					-rows => 3,
					-columns => 80),
		br (),
		submit (-name => "choice", -value => "Submit"),
		end_form ();
}
#@ DISPLAY_ENTRY_FORM