After the following description you will find several hyperlinks for further information, depending on how in depth of an explanation you seek.
If you have difficulties with attention, anxiety or obsessive thoughts, neurofeedback can retrain your brainwaves to calm your brain. If you have difficulties with depression, neurofeedback can help you retrain brainwaves to become more active. You actually have already done a form of neurofeedback when you learned how to ride a bike: that was neuromuscularfeedback. Your body received information from your surroundings, sent the information to the brain and helped your body adjust so you could balance and move forward on your bike so that you did not fall.
See the hyperlinks below for explanations and demonstrations of Neurofeedback:
You can also join the Facebook Group: Neurofeedback & Biofeedback Client: