As a side note, might I suggest using CGI.pm or a similar module for processing web forms and outputting HTML.

Here is your sample code rewritten using CGI.pm:

#!perl
use strict;
use warnings;

use CGI qw(:standard);

my $NumberOfTickets       = param('NumberOfTickets');
my $NumbersOnTickets      = param('NumbersOnTickets');
my $HighestNumberOnTicket = param('HighestNumberOnTicket');

print
    header(),   #The HTTP header
    start_html(
        -title => 'CGI/My First Form',
        -bgcolor => 'Blue',
        -text => 'white',
    ),
    p('Processing CGI form:'),
    p($NumberOfTickets),
    p($NumbersOnTickets),
    p($HighestNumberOnTicket);

my @lotto;
for(my $i_lotto = 0; $i_lotto < $NumberOfTickets; $i_lotto++){
    for(my $i = 0; $i < $NumbersOnTickets; $i++){
        $lotto[$i] = int(rand($HighestNumberOnTicket)) + 1;
    }
    print p("Your lottery ticket number is @lotto\n");
}

print end_html();
__END__
[download]

CGI.pm does all of the parameter parsing for you and provides for much neater looking code. Relying on the order of the params being passed to your script is probably not the best idea.