Windows 7 - Block facebook in my windows 7 server pc

Hi every one. I am using windows 7 64 bit. In that pc i have two lan where i get the internet from one lan and share the internet to my office callic through other lan. I try to block facebook so that no one from the lan are unable to access it. Can any one tell me how can i do this? I try with Employee monitor & also host file. But it only work on this pc. Not for the others. And it's impossible to get all of those pc and modify host file or install Employee monitor. I need to done in this PC. Can any one tell me how can i do this?

For HOSTS file blocking to work you would need to install the same HOSTS file on all machines... or you would need one machine with a dual-LAN card to act as a gateway to the router and internet

Does your router not support firewall options to block certain websites?

Beware that staff can still use proxy servers to bypass almost all restrictions you make...

Yes my windows 7 pc has two LAN card and act as a gateway to the router and internetcan one for share the net and another for get the internet. I try with firewall but i do not know how to configure my windows 7 firewall so that it can block facebook?
Or please tell me the available proxy server for windows 7 pc and how to configure it to block facebook or like some other site?

Your "gateway" machine must be set to share it's internet connection with the other terminals in the right way, otherwise all attempts at blocking will fail.

As for globally blocking proxy servers? You are joking I assume? You'd need a huge blacklist to achieve that.

Personally I'd block Facebook in the routers settings, not in any software.

have you tried the steps as below? :
open command prompt and type in the following >

it should look like the picture i attached (capture)
if you don't type it in the correct way it wont work.