You can add shapes to your videos either on the Advanced Editing screen or the Edit Scene modal.
Follow these steps:
Step 1: On the left panel, select 'Enhancers.'
Step 2: Select 'Shapes.'
Step 3: Select the category of shapes you want to add.
Step 4: Click on a shape to add it to the scene.
Step 5: Change the colour and opacity of the shape from the right panel.
To delete a shape, select it, and either hit 'Delete' on your keyboard or click the trash button on the right panel.