All servers listed on Minecraft.Buzz require Minecraft Java Edition and are free-to-join. Minecraft can run on Windows, macOS, Linux, and can be downloaded here!
Find a server you like, and copy it's IP address. After starting Minecraft, click on "Multiplayer", "Add Server" and paste the IP in the IP Address field - Click "Done" to confirm. You will be taken back to the servers list - You can now click "Join Server" to play on it! If you're facing any problems connecting, here's some troubleshooting tips.