Let’s add a background color. Of course you must use CMYK values to find the perfect color. Double-click over the Foreground color in the Tools Bar and select your background color.
I’m using a subtle combination of Yellow 15% and Plain Black 10%. Now draw a rectangle from the Top-Left corner to the Bottom-Right Corner of the Bleed Guides, by default the fill of that Vector Rectangle is the Foreground color. It’s very important to add the background including the bleeding margin.