How to activate WordPress Multisite in 3.1
To enable this feature, simply open your wp-config.php file located in your WordPress root folder using a ftp client. If you need help with ftp contant your web hosting company. I currently use HostGator and their support absolutely rocks. Then add the following line at the very bottom in the
define('WP_ALLOW_MULTISITE', true);
Once you have done that, make sure you deactivate all plugins.
Then you should be able to access the network page from Tools » Network
Select Sub-Domain and carefully follow the instructions because you will need to edit your wp-config.php and .htaccess files.
Now, you no longer need to install multiple copies of WordPress because you can run multiple blogs from one installation. By default, you would only be allowed to run other blogs as a sub-domain. To use other domains for blogs, you can use a WordPress Multisite Domain Mapping Plugin
