How to Add Section Background Overlay Color

You can easily set the overlay color with transparency for each section by just following the below instructions.

Activate the theme on your dashboard, then go to Appearance > Customize > Desired section ( the section in which you want to set the overlay color.)
Click on Background overlay Color option, select the color. Now simply you can set the color overlay by decreasing or increasing the transparency using the scroll bar.
You can choose overlay color for each particular section.