This feature can be used to create further domain under a website.
Go to → https://192.168.100.10:8090/websites/example.com
Repalce 192.168.100.10 with your VPS/Dedicated server IP Address. Alternatively navigate to Main > Websites > List Websites » Manage (the desired website). Scroll down and click Add Domains
Fill in all the details and click Create Domain. Here example.com is the master domain. If you leave the path empty, than document root for child domain will be /home/example.com/public_html/childdomain.com
And if you enter a custom path, it will be /home/example.com/public_html/custompath
Go to → https://192.168.100.10:8090/websites/example.com
Repalce 192.168.100.10 with your VPS/Dedicated server IP Address. Alternatively navigate to Main > Websites > List Websites » Manage (the desired website). Scroll down and click List Domains.