First, you have to be running the Pi edition of Minecraft on a Raspberry Pi on the same subnet as your LabVIEW code. This doesn't work with the full version of Minecraft.
You can download Minecraft for the Raspberry Pi at http://pi.minecraft.net.
Once its installed, start a game and load a world. This will start a server in the background.
In the Minecraft-Pi library, you create a Minecraft-Pi object using Init.vi in the Connection Methods folder. You call it with the IP address of the Raspberry Pi running Minecraft.
Once you have created the object, use Connect.vi to connect to the server. From there, if it didn't error, you are connected until you call Close.vi. You can use any of the other methods to set or read the available values. I included the "mcpi-protocol-spec" text file to explain how the functions work.
Beyond that, make sure you can ping your Raspberry Pi and that your networking isn't blocking the ports. The Minecraft-Pi server uses port 4711.