The Options toolbar button in the publish window presents a tool window for selecting colors, fonts, background image, and other options.
Options Window
To edit the color of individual cells, select a color for Custom Cell Color and then to enabled, toggle the button
with the paint bursh. Click on cells to paint them with this color. To undo, use right Click. When finished again
togggle the paint brush button.
Background Image
When selecting a background image, make sure the background color is transparent. Otherwise, the image will not be visible.