Adding new button to top-bar

Hi,
I want to add a new button ( Contact ) in the header top bar. And I don't how to do it. The theme that I am using is Fastor.

I tried to go to plublic_HTML > catalog > view > theme > fastor > template > common and I search through all the following files.
header.tpl, header.twig, home.tpl, menu.tpl. I could not find anything, infect header.twig is empty.
This is an ss of the header.tpl


What I did find is a nav tag with the links that I was looking for in plublic_HTML > catalog > view > theme > DEFAULT > template > common.
I added a new ul with the a tag but it still not works.

Did you clear all the caches each time?
https://www.antropy.co.uk/blog/how-to-c ... t-3-0-2-0/

Yes, I did

Switch back to the default theme and see by editing a TWIG file and clearing all caches if it makes a difference as compared to the custom theme you are using.