First you need to go to your site and click any post you want and see the simple heading and now you want to change the background. To do this, first you need to go to your word press admin and then click custom file editor in thesis options it will open your code window and here you will have to paste the code which is showing in the video. you will have to paste it in custom.css. After pasting the code you have to click the green save button. And its all done. Now you can see the difference in your post heading, the background has come there. If you want to change the color, go back to your code in custom file editor and see there the line of code written "background-color:" you can change the value of it whatever you want and click the save button again. It will change your heading background color.