How to customize my Moodle course header

Question

echo $OUTPUT->header()

I found this code, but I can't find the page that create the function.

I want to put a progress bar under the button:

I believe it is possible but which file I need to edit?

Answer 1

The header() method is defined in core_renderer class in moodle/lib/outputrenderers.php file. Your theme will be extending this class in an extended class in theme//renderers.php. You can override header() method in that class.