How can I make subdomain in PhpFox script?

How can I make subdomain in PhpFox script?
.htaccess file:

ErrorDocument 403 /index.php?do=/public/error/403/
ErrorDocument 404 /index.php?do=/public/error/404/

RewriteEngine On

RewriteCond %{REQUEST_URI} !^/file/.*
RewriteCond %{REQUEST_URI} !^/install/.*
RewriteCond %{REQUEST_URI} !^/design/.*
RewriteCond %{REQUEST_URI} !^/plugins/.*
RewriteRule ^index.php(/.*)$ /index.php?do=$1 [L]

RewriteCond %{REQUEST_URI} !^/file/.*
RewriteCond %{REQUEST_URI} !^/install/.*
RewriteCond %{REQUEST_URI} !^/design/.*
RewriteCond %{REQUEST_URI} !^/plugins/.*
RewriteCond %{REQUEST_URI} !^/index.php
RewriteCond %{REQUEST_URI} !^/robots.txt
RewriteCond %{REQUEST_URI} !^/favicon.ico
RewriteRule ^(.*)$ /index.php?do=/$1 [L]

PHP:

config.php file:

<?php
global $_CONF;

$_CONF = array();

$_CONF['db']['host'] = '********';
$_CONF['db']['user'] = '********';
$_CONF['db']['pass'] = '********';
$_CONF['db']['name'] = '********';
$_CONF['db']['prefix'] = 'phpfox_';

$_CONF['path'] = dirname(dirname(dirname(__FILE__))).'/';

$_CONF['domain']          = '************';
$_CONF['host']            = $_CONF['domain'].'/';
$_CONF['http']            = 'http://';
$_CONF['https']           = 'http://';
$_CONF['rewrite_engine']  = true;
$_CONF['path_translated'] = true;
?>

PHP: