Need help with topcat plugin ( changing colors)

Ive been looking for a plugin that allows me to choose on the fly ( as opposed to alternating) the background color of a post and title. The only one Ive found that can do that is topcat https://www.thunderguy.com/semicolon/wordpress/top-cat-wordpress-plugin/
But since theres no readme or documentation I have no idea what code is needed for tha tags and where to put them to define differant colors for the radio buttons. I only need something really simple like the ability to occasionally change the title or background post color.