You can add banner ads in thesis header. To do this, first go to your word press admin and click on custom file editor in thesis option. Now select custom_function.php in edit selected file option and click edit selected file. You will get a warning so to do this you need to use FTP. Go to the path in FTP which is showing in the video and then click on Launch.php and now copy the code which is showing in the video and paste it in the launch.php. But you have to change your header image path in the code. Now close your file and click on save to save it. Now again go your custom file editor in word press admin and paste the code which is showing in the video and click big green save button. You can now see your site for the changes.