Some people believe they can exist on the astral as spiritual creatures. That's open to debate, and "dragon magic" isn't like in tv shows and all that, it's more of a spiritual path from what I've seen, well most magic is but dragon magic didn't really involve any spells or what not. Correct me if I am wrong.
First you need to find a dragon. To do this you would need to astral project and focus on ones energy to locate it. You must approach a dragon with respect and the need to learn and be guided.
The rest is really up to you. Theres alot more on dragon magic but these are basic needs. I'm sure someone will go into more depth on the subject but if not, contact me and I'll write you a whole manual. :)