How to Enable Multisite in WordPress 3.0

Follow the simple 10 minutes max. instructions to activate Multi User functionality in your WordPress 3.0 installation:

1. Disable all plugins. You can re-enable them after multi-site has been configured.
2. Activate the multi-site features of WordPress 3.0 by adding this line of code to your wp-config.php file:
   

   /** Enable or disable Worpress Multi-site features **/

   define(‘WP_ALLOW_MULTISITE’, true);

3. Refresh your Dashboard then visit Tools -> Network. You will see a screen that looks similar to the one in the picture below. Read onwards before you make any configuration changes.
4. If you want to install your additional blogs on sub-domains instead of sub-directories you will need to create a wildcard DNS record on your server to enable the virtual host (sub-domain) functionality of WordPress 3.0. Your server must support wildcard DNS records for you to do this.
5. You need to install the now activated WordPress 3.0 Network settings◦Find the Network settings page in your WordPress admin panel (Tools -> Network)◦Choose whether you want to use sub-domains or sub-folders for the additional blogs

   ◦Type a name for your network of sites

   ◦Set your admin email address

   ◦Click “Install”

6. After a minute or two you will be presented with a configuration screen. Back up your .htaccess and wp-config.php files before you proceed to follow the instructions provided on that configuration screen.◦As a precautionary measure to prevent visitors of non-existent sites from being greeted by 404 error messages, redirect them to a URL of your choice by adding the below code to the bottom your wp-config.php file:
   

   /* Send visitors to non-existent blogs here */

   define( ‘NOBLOGREDIRECT’, ‘http://yourdomain.com/’ );

   change http://yourdomain.com/ to the main blog you want to redirect to.

◦Log out then log back in.

You will now need to go through your settings to enable or disable the new options provided by WordPress Multi Site.

Here is also video to setup mulitsite by Devin