To change the color of the background for your story, first you need to tap on the edit button ("paintbrush"):

Then, you will find a button to change the background.

First, you need to click on the edit button ("paintbrush"). Then, you have to tap on the "colors" button:

After clicking on the colors button, you will be able to choose from different colors that our app provide or add the color of your choice by adding a "hex code" color.