Click on the little symbols to customize your character. Use the sliders to customize the color of certain things. Once you're done, press the green check mark on the bottom right and you're free to take a screenshot and use it as your icon! However, there are rules to using it as your icon: 1. make it appropriate 2. have fun! - Do not press the stop sign - it will revert your colors to red.
Thanks to @oaccoderms and @Berricake :)
