How to configure proxy in web browser (Windows, Mozilla Firefox)?

Open the menu in Mozilla Firefox, and click the Options menu.
Click the Advanced menu.
Click the Network tab.
Under Connection, click the Settings... button.
Under Configure Proxies to Access the Internet, select the Manual proxy configuration option.
In the HTTP Proxy box, type the IP address or Hostname of the proxy server.
In the Port box, type the port number that is used by the proxy server for client connections.
Select the Use this proxy server for all protocols check box.
You can type in the IP address to bypass the proxy connection in the No Proxy for box.
Click OK to close the Connection Settings dialog box.
Click OK again to close the Options dialog box.