##

  login=                         (text)
  pass=                          (password)
  secure_login=0                 (radio) [1/SSL |*0/Non-SSL]
  =               (image)

##

##

# Fields to fill out, since there is only one button,
# try to let Mech find it
$mech->submit_form(
        form_name => 'loginForm',
        fields => {
                    login => $user,
                    pass => $passwd,
                    secure_login => '0',
                  },
)->is_success() || die "Unable to login to $login_page, stopped";

# Ensure we've logged in successfully
my $logout = $mech->find_link( text => "Logout" );

die "Did not log in, stopped" unless $logout;

##

##

If there is only one button on the form, $mech->click() with no arguments simply clicks that one button.