You can add overlays to your scene either on the 'Edit Scene' modal or the 'Advanced Editing' screen using the same process.
Here are the steps for the same:
Step 1: Select the scene to which you want to apply the overlay.
Step 2: On the left panel, under the 'Elements' tab, click 'Overlays.'
Step 3: Select a category of overlays.
Step 4: Hover on an overlay to see a preview.
Step 5: Click on an overlay to add it to your scene.
Here is a video to help you through the process: