Sounds like you've got a misunderstanding.
in reply to Have CGI call script, display status in browser
Point the form you are submitting to the cgi script you want to run. E.g. <form action='foobar.cgi' method='post'>
Then make the script parse the form inputs and print out an HTML page. E.g.
# this is foobar.cgi
my $cgi = new CGI;
print $cgi->header, $cgi->start_html;
print "You entered " . $cgi->param('form_input_name') . "<br>";
No need to use system.