Add new widget area - how do I change BG colour?

Hi,
I added a new widget area to my site with four cells.I want to change the colour as at present it shows the background through the widget area.

The area I'm adding it to it the header - between my tagline and categories. Any help would be much appreciated!

My site is www.toxinfreefuture.com I've removed the new widget area until I can figure this out, but you'll see the background with the green design - it is what is showing and I want it all red as is the rest of the header area.

Thanks

Sue