use strict;
use CGI qw(:standard);

print header, start_html, start_form;

if (my @checks = param('checks')) {

   print checkbox_group(
      -name      => 'myName', 
      -values    => \@checks,
      -linebreak => 1
   );
}
else {
   print textfield('checks'), "<br>" for (0..4);
   print submit;
}

print end_form, end_html;