How? That is up to you: A will is a legal document that determines how your assets and your estate are distributed after death. 

Where, so much law firm in China, also foreign lawyers, who can help you. English speaking Chinese lawyers.

Advice: better get tax planning and investment advice mostly that is more efficient and those companies also offers you sometimes in house set up a will. Because circumstances changed. 

Feel free and drop me a message if you need assistance. 

Moon, what type of question is that, point being you are a foreigner, how in the world would you or your country be able to uphold any ruling or documentation?

We went to a Chinese lawyer, we needed the original paperwork for everything we owned (property in UK and China), we needed the passports and birth certificates for everyone involved and a huge amount of translation work (organised by the lawyer 'at cost') then a significant amount of cash. (16,000RMB in total iirc).

The whole process took about 8 months and was relatively painless, apart from the wallet emptying section.

Of course you can. I have a will and also instructions on what to do if I need to go to a hospital, life support systems usage, how and where to be buried, etc.

I wrote out in English detailing what I wanted done (like an open will in USA) and who gets what. Then, a Chinese Lawyer friend of mine had it translated to Mandarin, and with the appropiate witnesses' signatures, notarized. Then he filed it at the Local Court. Of course, to make it simple I just listed assets within China. Those in USA are covered by another one there.

I am sorry but can not tell you how much I was charged for this effort, because I paid nothing. I had referred a few fellows to this lawyer in the past, he had insisted in giving me a commission, but I refused it. When I wanted this done, he told me if he can do it on his free time, there will be no charge. And since I was in no rush to die, I agreed to it. It took him almost a month to do it, and for free.