US Permanent Resident with Canadian Citizenship Traveling to China

I am flying from Toronto to Shanghai in June for a three week trip.

I am a US Permanent Resident with Canadian Citizenship, travelling to China in June. Though I was born in Canada, I currently live in Massachusetts. My family is not of Chinese descent.

Being a US Permanent Resident but also a Canadian Citizen, what documentation do I need to fill out, and what do I need to submit? Will everything go to the U.S. Consulate in New York?
Thanks!