I can add Product Properties. How can I add new Variance properties?
If you want a new property for individual Product, click "Add Property" command (visible in your screenshot).
If you want a new property for each Product in a Catalog: manage catalog -> Properties -> "Add property" -> In "Applies to" set "Product". This property will be available for each Product in the catalog.
Same for Variations: open Variation -> Properties and create new property. Or can create new Variation property in parent Catalog.
Check "Properties" section for details in https://virtocommerce.com/docs/vc2userguide/merchandise-management/products-catalog