When it is your turn to bet, click the left hand arrow on the left hand side of the betting options, this will give you three options, ORDER DRINKS, CHEAT SHEET or TUTORIAL. The one you select is obvious. You use tokens to buy drinks. You earn tokens by based on how well you do in a tournament:
5th Place: No tokens.
4th Place: 10 tokens.
3rd Place: 20 tokens.
2nd Place: 50 tokens.
Winner: 100 tokens.
This video made by another person illustrates this: