How can I set up a proxy server in Mozilla Firefox?

@bertha 

To set up a proxy server in Mozilla Firefox, follow the steps below:

1. Open Firefox and click on the three horizontal lines in the top-right corner of the window.
2. Click on "Options" from the dropdown menu.
3. Scroll down to the bottom of the page and click on "Settings" under the "Network Settings" section.
4. Select the "Manual proxy configuration" option.
5. Enter the IP address and port number for your proxy server in the "HTTP Proxy" field.
6. If your proxy server requires authentication, check the box next to "Use this proxy server for all protocols" and enter the username and password in the "Username" and "Password" fields.
7. Click "OK" to save your changes.

Your browser should now be configured to use the proxy server you specified. You can test the connection by visiting a website and verifying that it loads properly.