The Add a Zone button allows you to create new zones. It will bring up a dialog box.

Type the name of your zone at the top of the box. Should you forget to add the "." after the top level domain name, QuickDNS will add it in for you.

Select your slave servers using the checkboxes next to each of the servers that you are currently connected to, and click the Create button. This will bring up a Zone window, which you can then start adding records to. You can also create new zones with the New Zone item in the File menu, or by clicking on the Assistant button in the Manager window.