Neurofeedback involves placing electrodes on different areas of the brain and rewarding and/or inhibiting certain brain wave frequencies (alpha waves, theta waves, beta waves, delta waves, etc.) by doing this you literally retrain your brain and change its architecture and structure through the principle of operant conditioning. What it looks like for someone receiving it would be someone just pasting electrodes to certain areas of your head, and then you sit there and hear a series of beeps based on the EEG activity in those portions of your brain where the electrodes are located. A beep is a "reward" and your brain tried to "achieve" that reward. Because our brains are neuro plastic and can grow, you begin to rewire your brain. It's usually about 150 a session if you see a licensed practitioner. Read the neurofeedback page on Wikipedia