To start a new game on the Toad Kingdom board, you will need to select "Play" on your main screen and then "Toad Kingdom".
Once you do so, a new pop-up window will open, from which you can choose your opponent to finally start the game.
This board will challenge you to collect 15 mushrooms, get to the Toad King and claim victory before your opponent. For each correct question you answer, you will get a mushroom.
In case you reach the Toad King and you haven't got the 15 mushrooms, he will challenge you by serving you as many questions as mushrooms you are missing to reach the required number. For example: If you arrive with 10 mushrooms, you will have to answer five questions correctly to get the missing mushrooms; if you answer them correctly you will win, while if you answer incorrectly you will have to go back to the beginning of the board to get the missing mushrooms and climb up again.
While this board can be quite a challenge, it's important to know that you can find a lot of coins and reward chests along the way, as well as a bigger prize for winning the game.