Peace. I don't know how to use a function that gives the robot an instruction to follow a line.
I would love if anyone would give me advice.
Thanks in advance.

Check out this forum thread:
https://forum.dji.com/thread-193980-1-1.html

The Hunter example in the Lab has all the code required to follow a line. In my case, I modified the speed (3m/s) down to 2 m/s because of the curves I had put on my course.