How do you set up/create an alliance v alliance game?

Hi I was wondering how you create an alliance versus alliance game. Specifically how do you challenge the other alliance?

Our main game creator is offline and i need to set up an alliance versus alliance game. Is the usual go to create game and set up advanced options etc but how do i challenge the other alliance or make sure it is a ranked alliance game.

Any helpful suggestions would be greatly appreciated.

Thank You

Mr Selfridge