Follow the steps below to create a new case type form:
Open the App Designer by navigating to Settings > Applications. In the Applications List, select an application and click App Designer to go to the Application Configuration page.
In the left application component panel, there is a header for Case Types; click the name of a specific case type to open the Case Type Configuration page.

In the left case type component panel, there is a header for Forms; click the menu icon next to the header to show a dropdown list of options. From the list, click New to open the UI Designer to create a new form.

Select a form type. Five (5) different Form Types are supported by UI Designer (Case Form, Offline Form, Portal Form, Attachment Form, Action Form; see below for more details about each Form Type).

Click Next to finish the initial form configuration and open the UI Designer to begin customizing your form.