The easiest way to understand acupuncture is as a physical manipulation of the body (like massage) that is used to produce a change in some aspect of how the body is functioning. This includes the use of needles to release knotted muscles, change connective tissue alignment, affect the internal organs, calm the mind, and more. The techniques utilized by the practitioner and the areas chosen for treatment are what determine the affect. Neither the needles nor the acupuncture points themselves do anything on there own.
We can produce similar results using hand techniques, the application of oils or liniments, cupping, or other modalities, but acupuncture needles are often an expedient, allowing the practitioner to accomplish more in less time.
Acupuncture is one modality amongst many that Chinese medicine practitioners use. It is highly effective, but it is important to remember that it is only a tool - it is not the medicine itself. Chinese medicine is a broader system that is based upon an understanding of the relationships between different aspects of the mind and body internally and how each mind-body interacts with the external environment.
In my opinion, the beauty of this system of medicine is its ability to integrate anything and everything into a cohesive system of thought, allowing us to understand a large number of factors influencing a person and how any number of approaches can be used to help them.
As for where to learn acupuncture, there is much to be said on that topic. I would be happy to speak with you at some point about that if you are interested. Feel free to contact me if you would like to do so.