You can create inner classifiers in a class or interface in any of the following ways:
Open the Inner Classifiers tab in the property sheet of a class or interface, and click the Add inner class or Add inner interface tool.
Right-click a class or interface in the Browser, and select or
Select the Inner Link tool in the Palette and click and use it to connect two classes in the diagram. The first class will become a composite class and the second, an inner classifier
Create a composite classifier diagram dedicated to the class (see following section), and create classes or interfaces there.
All inner classifiers are listed in the bottom of the class symbol