This will either be your very first multiplayer achievement or the very last achievement you get in the game. Just like the description says you have to win the very first multiplayer game you play. The easiest way to get this achievement would be to find someone who already has the achievement and have them let you win your first multiplayer game. If you are unable to get this on your first multiplayer game you will have to uninstall and reinstall the game, but this will erase all your progress in the game. So you will want to wait to do that until you have all the other achievements to do that. If you need a boosting partner you can find one here.