In the Data Model & Catalogspage you can create a Class.
When you access the Data Model & Catalogs page, you will be asked to select a model type to edit.
Creating a Class
Follow these simple steps to create a Class.
Click on the Add New button in order for the system to drop a class onto your canvas.
A new window will open. In this screen you need to insert the Class name.
Add an Attribute element directly from your Class just by clicking on "Add Property" Button.
After you add an Attribute, a new window will appear requesting additional information.
Press Save to finish creating a Class.
Learn more about how to edit an Attribute.