1. Install FoxyProxy Standard from the official Firefox Add-ons page.
2. Open the FoxyProxy toolbar menu and select Options.
3. Open Proxies and select Add.
4. Choose the proxy type shown in your Proxy-Cheap dashboard, then enter the server address and port in the matching fields.
5. If the proxy uses username/password authentication, enter the proxy username and password from the dashboard. If it uses IP whitelist authentication, leave those fields empty and confirm that your current public IP is whitelisted.
6. Save the proxy profile.
7. Open the FoxyProxy toolbar menu and select the saved proxy for the websites or browsing mode you want to use.
8. Open an IP-check website in Firefox and confirm that the expected proxy IP or exit IP is displayed. If you use URL patterns, per-tab settings, or containers, make sure the proxy also applies to the page where you are checking your IP.

If the proxy does not connect, confirm the protocol, server, port, authentication method, and credentials. Use a proxy-DNS or remote-DNS option for SOCKS5 only when your setup requires it and FoxyProxy provides that setting.