Failed to install

[mac_man2008 at yahoo.it]

Hi to all,
I am in China and I just followed the instructions reported here:
http://www.nginx.org/en/download.html
but after running the "sudo apt-get update" command I get the following 
error:

W: Impossibile recuperare 
http://nginx.org/packages/debian/dists/quantal/nginx/source/Sources 404  
Not Found

W: Impossibile recuperare 
http://nginx.org/packages/debian/dists/quantal/nginx/binary-i386/Packages 404  
Not Found

E: Impossibile scaricare alcuni file di indice: saranno ignorati o 
verranno usati quelli vecchi.


What can I do?
Thanks.
Kubuntu 12.10