Open Internet Explorer by clicking "start," "All Programs" and "Internet Explorer."
Click "Tools" and "Internet Options."
Click the "Connections" tab.
Click the "LAN Settings" button.
Uncheck the "Automatically Detect Settings" checkbox by clicking it.
Click "Use Automatic Configuration Script."
Type "file://c:/proxy.pac" into the "Address" box, replacing "c:/proxy.pac" with the full path to the PAC file on your computer.
Click "OK" twice.
Navigate to a website using Internet Explorer to confirm that the PAC file works properly.
Open Mozilla Firefox by clicking "Start," "All Programs," "Mozilla Firefox" and "Mozilla Firefox."
Click "Tools" and "Options."
Click the "Advanced" icon at the top of the options window and click the "Network" tab.
Click "Settings" to the right of "Connection."
Click "Automatic Proxy Configuration URL."
Type "file:///c:/proxy.pac" into the box under "Automatic Configuration URL," replacing "c:/proxy.pac" with the full path to the PAC file on your computer.
Click "OK" twice."
Navigate to a website with Firefox to confirm that the proxy settings are correct.