The opacity feature is available from the Composition mode; on the Cartesian data board. It enables you to modify the opacity of the elements.
If you wish to change the opacity of all the aspects of an element, select the element in the Elements column and change its opacity.
On the contrary, if you wish to change the opacity of one of the aspects of an element, open the drop-down list of the element to see its different aspects. Then click on the aspect you want to modify and change its opacity.
Moreover, using the Animation tools, you can animate the opacity of an element or its aspects.