By some edits to wp-config.php file
define( 'WP_ALLOW_MULTISITE', true );
define('MULTISITE', true);
define('SUBDOMAIN_INSTALL', false);
define('DOMAIN_CURRENT_SITE', 'localhost');
define('PATH_CURRENT_SITE', '/plug/');
define('SITE_ID_CURRENT_SITE', 1);
define('BLOG_ID_CURRENT_SITE', 1);
Then you will see a 'Network Setup' option under 'Tools' menu of wordpress dashboard. By following the instructions you will be directed. edit your '.htaccess' file in WordPress and lastly you will be able to set multisite in your WordPress.