It's all in the index.php file since it's controlled by a variable in the configuration. Just search for #s5_top_row1_area1 when editing the index.php and it will take you to that section.
I am facing the same problem here. i want to inset a shadow over my background image (top_row1_area1 ). i tried editing the php file but i have no idea what am doing.
any help please. thanks