Before cards are dealt, two players must put money in the pot to start the action. These are forced bets.
When it is your turn, you have specific options depending on what previous players have done.
Pass the action to the next player without betting. Only allowed if no one has bet yet.
Put the first chips into the pot. Others must now match your amount to stay in.
Match the current highest bet to stay in the hand.
Increase the current bet. Others must now pay more to see the next card.
Give up your cards and lose any chips you put in the pot. You are out of the hand.