@Diane: You can control widgets from “Appearance => Widgets” and add/remove widgets as per your need.
You can only put in the available widgets in your sidebar. If you want to add custom widgets then you might need to search for plugin that does it or you need to hire customizer to add extra widget for you.
You can change color as per your need from “Appearance => Theme Options => Color Options”.
For more details please try to add in your site URL and explain. It’s very hard to imagine and give you the solution.
.
