Your brain already does this automatically
Bend your elbow and touch your nose with your pointer finger.
How did you do it? Specifically, how did you simultaneously relax your triceps, contract your biceps, ignore your other shoulder and forearm muscles, and guide your arm smoothly and safely to the exact location of your nose?
Your brain did it automatically, just because you wanted it to happen. Neurofeedback works the same way: with the right tools, your brain can automatically improve its own activity, just as it automatically raises your heart rate during a scary movie.