How can I get a visa to China? i have an argentinean passport, but im in New Zealand.

You need to check consular district of Chinese embassy and consulate (https://www.travelchinaguide.com/embassy/newzealand.htm), and submit your application accordingly. You can either go in person or by someone else/travel agency with your residence permit or valid visa for NZ. To post application to visa office is also ok.