When changing background colors, you can change the background colors for the blocks themselves, the layout sections, or the entire email itself. To change the colors of the entire layout or layout sections, click on the paint bucket button . You can then choose from a set of swatches for preset color schemes.
Or, to give you more control, you can individually change the colors of different layout sections below the swatches.
Subsequently, you can always change the background color of each block by utilizing the block tools, when editing a block.