Playing a game at a slot machine is really easy. 

Use the Bet One button to increase the number of coins you are about to wager by one. If you are already wagering the maximum number of coins clicking the Bet One button again will set the number of coins to one.

Use the Bet Max button if you intend to wager the maximum number of coins for this slot machine on the next spin.

When this is done start the game by clicking the Spin button.