You need to either go to the Chinese embassy in the U.S to apply for a tourist visa or you can find an agency that will mail your passport and application form to the embassy (they will email the passport with the visa inside back to you).

I believe you can get a 30, 60 or 90 day visa. I'm not sure on the exact number of days.

Good luck!

Here is the information from the Chinese embassy in the United States for your Tourist Visa:

http://www.china-embassy.org/eng/hzqz/zgqz/t84246.htm

Follow the process exactly, because any deviation will result in having your application denied, and no explanation as to why. Of particular interest to you will be part 2, where you can submit your application (in person or through an agency), depending on state of residence.

I had my initial tourist (and then work) visas processed through this agency in California. Very helpful and professional. Here's the URL:

http://www.timelyvisa.com/

Good fortune with the process. If you want to know more about Changsha, PM me. I've lived here for a while.

I'm not sure about from USA, but from Canada you can only get a 30 day tourist visa first time. It may be extended while in China.