How can I add shared categories?

Adding a shared category is similar to adding an existing category except the category is selected from the catalog that has been designated as a source catalog.

The sharing content attribute value determines what content is shared from the source catalog. A category within a source catalog that has been added to a native catalog is also known as a referenced category. You use the list of values from the Add Categories menu. The Shared Category option will be disabled if the catalog has not been configured for category sharing.