Removing gray squares from Background

I want to change the color of my background. I DO NOT want the gray squares and have tried many different things to remove it. I have read the forum's and many people have given advice, but none of them work. Please help. We want it to be a solid color. NO SQUARES.

 

Hello,

Paste this code in Custom CSS
Appearance > Theme Option > Styling Option > Custom CSS

Code:

body {
background: red!important;
}

Inplace of "red" put your color code.