If you're not familiar with Overlays, they are shapes and patterns you can use on your photos to add another level of creativity.
Step 1: Upload an Image into the Photo Editor.
Step 2: Select the Overlays Tab.
Step 3: Once you've selected your overlay, click on the adjustment bar to change it's Color, Opacity, and Size. You can also move the overlay around the image by clicking and dragging it with your cursor.
Step 4: Adjust the Rotation, Add Blur and Shadow.
Step 5: Click the blue checkmark to apply.