1. Go to onMessage > hover over Website > click Website name
2. Go to the page > click the edit icon > Edit Page Settings
3. Click the paint brush to go into style
4. Click Edit Styles > select Rows radial button
5. In the drop down (upper left) select the style to apply to the row > Save

Now that row style is applied to the row on the page, it will display behind the main page content.