I add banners and offers to my header for products and services to almost all of my sites and, because I am not very technical, I play with the editor for some.  To add a banner to a wordpress site this is a fast and easy way.

You’ll need to move things around in your editor to see where to place the code exactly for your own purposes but if you are adding a banner to your wordpress site and there is no quick and easy in the customizer section, or if there is nothing in the theme that gives you the option, then see if this makes your life just a little easier and makes it possible to generate some revenue with a banner in the header of your word press web site.