Which File Does The Simple Banner Text Update?

Hello,

I am trying to figure out which file gets updated when I insert a simple banner text. Using developer tools, it looks like an HTML entry.

If that’s the case, do I need to edit my theme’s header.php file? Functions.php?

I am trying to understand this from a learning perspective. I understand I can edit the text in the simple banner textbox, but I don’t want to.

I just want to know which file my html simple banner text gets inserted to if any.

Thank you so much for your help in advance!

Joe