Center area background color

http://www.housecallvetcare.com

I'm trying to change the background color of the center section. I understand this is a post element and is actually a table cell, so I'm a little lost. I can't think of the best way to write a style element or set a color preference.

I'm hoping I don't have to change the background color to my preferred color and then turn all the other elements to white background.

HAAALLPPP!

I already searched like crazy in this thread, "center background color" "cell color" "table cell background" "background color" and still can't find it!

Thank you so much in advance--

S.