so how does traditional Chinese medicine work then?

Well, yin-yang is perhaps the most general of several key concepts.
The holistic approach of Chinese medicine means that both mind and body are seen as interconnected.

The passions chronic fear, sudden fright, anxiety, over-excitement, over-thinking, sadness and irritability - are seen as both the cause but also the symptoms of internal disharmony and illness.  You may be feeling a lingering sadness due to a lung condition, but equally the emotion may be physically weakening your lungs.

So, when you meet a Chinese medicine practitioner they are just as likely to ask you what mood you're in as they are to listen to your chest.

is diagnosis different to western medicine?

Traditional Chinese medicine often refers to the four pillars.  These are: looking (at the facial colour, the skin, the tongue), smelling (the breath, the body odour), palpation (for example feeling the wrist pulse), and listening (to the patients symptoms but also to the tone of the voice or the sound of a cough).

These methods enable a practitioner to assess the physical, psychological and energetic state of the patient and are often used together with Western diagnoses to form a powerful combination of disease detection.

The idea of organ networks is another central concept and was developed by ancient Chinese to explain the relationship between a healthy body and a healthy mind.

how are the organ networks used?