1. Log in to your account at https://ac.mediatemple.net/login.mt;
2. Click on Domains at the top of the page;
3. Click Admin next to the domain you want to add a subdomain to;
4. Go to Edit DNS Zone File;
5. Click on Add row, then enter the following information:
Name: what you want to name your subdomain, it can be www or any relevant name;
Type: select CNAME from the drop-down;
Data: secure.pageserve.co in order to point to our servers.
Now just click Save Changes and you're done.