Hello,
Please login in to the Webmin control panel to create/add a new domain/site. Once you are logged in you then want to select Servers and the "Apache Webserver" from the options on the left menu.
You several options for administering the Apache Webserver. The first option of "Global Configuration" the next option is to edit any existing virtual hosts that have been setup. The last and 3rd option of "Create virtual host" is what you want to pick to setup a new website.
Here you can able to create a new domain.
Now, you have successfully created new domain.
Thank you,