use strict;
use warnings;

use URI::file      qw( );
use WWW::Mechanize qw( );

my $mech = WWW::Mechanize->new();
$mech->get(URI::file->new_abs('file.html'));

$mech->form_number(1);
$mech->field("headline","MyHeadline");
$mech->field("thecontent","MyContent");
$mech->field("categories[some_tag]","Blah");
$mech->click("publish");

print $mech->response()->request()->as_string()