Instructions
Press the "Alt" and "Tab" keys on your keyboard at the same time. This will minimize "Minecraft" to the desktop.
Click the "Start" button.
Click the "Run" button, then type "CMD" into the dialog box and press "Enter."
Type "Ping" followed by the IP address of the "Minecraft" server you are using. You can find the server IP address at the "Minecraft" server selection screen.
Press "Enter" on the keyboard, then wait while your computer connects to the server. The ping will be listed next to the "Time = ##ms" with the ## being replaced with the ping.