Proxy in nginx

Hello, i want to make proxy to my service users that will work as:
User > fast.mydomain
fast.mydomain return to my user file list (autoindex)
user chose file what want download and fast.myhost send him this file
on this track:
fast.mydomain > my proxy server > user

Is possible to configure this on only nginx on two serwers
(fast.mydomain and my proxy server)?

Marcin Janowski(WMP)