Each theme has different “Widget areas”, so if the theme you are using doesn’t have the one you would like, there are unfortunately not so many options. Or at least, not without editing the template files.
I found this plugin: https://wordpress.org/plugins/custom-widget-area/ which seem to do what you need, although it hasnt been updated in a long while, so might work or not, but seem worthwhile to give a try…
Other options would be, as mentioned by the webmaster who answered, to change theme to one that has a widget area in the header.
If you have a lot of other changes to do to the template might be a good idea to learn how wordpress template work, and get some basic notions of html, css and php. There are plenty of resources, personally I have used lynda.com and https://learnable.com/.
If you don’t have so many changes as to make it worthwhile the investment time, and don’t want to mess with code, I would recommend you hire someone to do it for you.