my $ua = LWP::UserAgent->new;
$ua->env_proxy;

 
my $response = $ua->post($GATEWAY_URL, {
                         # add other parameters as necessary
                         'USER' => 'myid',
                         'VENDOR' => 'myid',                         
                         'PARTNER' => 'partner',
                         'TRXTYPE' => 'S',
                         'AMT' => '$paymentamount',
                         'PWD' => 'mypass',
                         'CREATESECURETOKEN' => 'Y',
                         'SECURETOKENID' => $sec_token_id } );


print "Response: $response<br><br>";