Hello eyesforcars,
Thank you so much for using our theme SuperMag.
You can only change the header add image. https://doc.acmethemes.com/supermag/#HowtoaddHeaderAdvertisement
But you are not add code there on our free theme. You have to write custom code to add the code section instead of header add banner.
If you go to our premium product SuperMagPro we will provide you the child theme with the options to add code instead of header add image. Our premium theme have lots of additional features. Please check our product too. http://www.acmethemes.com/themes/supermagpro/
Note: Child theme is recommended to customize theme.
Best Regards,
Acme Supports