Scoring

If you mean the number in the center then this is how I would do that:

First I would add a True/False trigger at the end of section so it goes from False to True when that section is complete. If course is linear (ie it has to completed in order) you can just put this on last interaction of the last slide of the section (It could be the Next-button if that takes back to main menu).

Then I would make a number variable that starts as 0, and each time that one of those section tracking True/False triggers changes, 1 is added to the number variable. Then I would show that variable with reference to it on screen. If there are 4 sections, I would just write /4 after that variable, so it would appear to look anything from 0/4 to 4/4 as needed.

As simple .story-file to show this. I the actual course those buttons would take you to another sections, and at the end of the section there would be that True/False-trigger. Now it is there right in the button, just by clicking a button you "complete a lesson".