Creating a Sub-Domain through version 4 of the Helm Control Panel is quite similar and very simple to version 3.
Log into Helm as Admin, and on the main window, click the icon for My Domains.
Click on the domain you would like to create the alias for. For this example, we will use test-domain.com
Click the icon for Sub Domains.
As you can see, there are currently no existing Sub Domains for this domain. Click Add in the upper right-hand corner of the window.
Enter a name for the Sub Domain. For the purposes of this article, we will be creating example.test-domain.com. Once entered, click the button in the bottom right-hand corner which says Save.
You will now see the Sub Domain has been added. You can verify it has been created by opening Internet Information Services (IIS) Manager.
Open IIS by Navigating Start / Settings / Control Panel / Administrative Tools / Internet Information Services (IIS) Manager 7.0. Once open, click the plus sign next to Computer Name to expand it, then click the plus sign next to Sites, and then the plus sign next to the domain in question. You should see the Sub Domain is now a folder under the main domain.