Customize header top menu (adding external shortcode)

Hi,
I am trying to add some custom code in the header but I am not getting it.
The idea is to show the price of the dollar after the date in the header top bar menu, like this: https://wetransfer.com/downloads/9f62ae37424597efe69f69c3d7f6901220191218185025/0e4098
How to add custom code in header top bar menu?
or How to create custom tagDiv element to put in there?
Thanks!

[Dollar quote from a third party:]
<!-- COMIENZO codigo cotizacion personalizado -->
<style type="text/css">
/* color de la moneda */
.cotizacion_personalizada {color:#dedede; }
/* color de valor de la moneda */
.cotizacion_personalizada A {color:#ffffff; text-decoration:none}
</style>
<span id="cotizacion_personalizada" class="cotizacion_personalizada">
Dólar ${dolar_c} / ${dolar_v}<br>
</span>
<script src="http://www.dolarcito.com.ar/scripts/cotizacion_personalizada.js" language="javascript" type="text/javascript"></script>
<script language="javascript" type="text/javascript">show(s_cotizacion_personalizada)</script>
<!-- FIN codigo cotizacion personalizado -->

Thanks Calin,
I have tried and finally I have been able to reach a good result.
I loaded a “header template” from “tagDiv Cloud Library” and edited it with “tagDiv Composer” until I got a result close to what I wanted. Then I edited one of the files in wp-content / plugins / td-cloud-library / shortcodes / header to embed the custom code.
The problem now is that when you load the page, the header is initially displayed higher than it is.
While loading https://snipboard.io/xgy6pl.jpg
Once you finish loading https://snipboard.io/w2UGmT.jpg
I tried to delete the modifications made to the php file (raising a backup), load a new “header template” from “tagDiv Cloud Library” and leave it as it comes but I always get the same result. Only when I use the default header does this not happen.
Why does this happen? What can I do to avoid it?
Thank you!