As promised, here is the step-by-step guide on how you can set up your Firefox browser for proxy server usage.
Run Mozilla Firefox. Go to “Tools > Options“.
Click “Advanced“. Then click “Network” tab. Next click “Settings” button under the Connection section.
>
Check “Manual proxy configuration:” and “Use this proxy server for all protocols“. Enter the HTTP Proxy and Port field according to your choice earlier. Click “OK” and you’re done!