im trying to add a wildcard subdomain system to my webserver, but its still not working,

this is the steps i took:

i made a new file vhost.conf in the directory var/www/vhosts/www.example.com/conf/vhost.conf

and i put

ServerAlias *.domain.com 

then second of all i made a new dns wildcard on plesk

CNAME *domain.com example.com

and then i edited my .htaccess file

Options +FollowSymLinks
RewriteEngine on
RewriteCond %{HTTP_HOST} ^(^.*)\.example.com
RewriteRule (.*)  user.php?user=%1

normally my url would be

http://www.example.com/user.php?user=solomon

but now i want to like this

http://solomon.example.com

but the steps i took still deosnt work

:)) whats happening here