You can create interesting effects by making objects more or less opaque. When you put a low-opacity object on top of another object, for example, the bottom object shows through.
Select an image, shape, text box, line, arrow, or video.
If you select a text box, everything in the text box, including the text and any background color, is changed.
Click the Style tab at the top of the sidebar on the right, then drag the Opacity slider.
If you don’t see a sidebar, or the sidebar doesn’t have a Style tab, click 
in the toolbar.