If you want to use wildcard subdomains and point them to your website make sure you have the following.

Make sure you have a wildcard DNS entry in Domain > DNS. You can add one as follows:

  1. Set the “Record Type” dropdown to “A” and klick the Add button.
  2. In the next screen enter a * (asteriks) in the domain name field, and enter the IP address your subdomain needs to point to.

Next, you need to create or edit the vhost.conf file for the domain. The file is located at /home/httpd/vhosts/<domainname>/conf/vhost.conf: Open it, and add the line ServerAlias *.<domainname>.
Now run the following commmand:

/usr/local/psa/admin/bin/websrvmng -a -v

Now all you need to do is restart apache.