You can bet or raise in a variety of ways. When it is your turn at the table, you will be presented with these options as shown below.
Clicking any of the basic actions (red buttons) will do exactly what they say: Call, Check, Raise To, or All In. Please note not every button will be visible all the time. Call or check will be visible, and Raise To or All In will be visible, each dependant on the situation you are in at the table.
Clicking any of the quick bets (black buttons) will adjust the amount in text box above the 'Raise To' or 'All In' basic action. Once you click these buttons, you must click the 'Raise To' or 'All In' button to bet that amount; it does not automatically bet that amount for you. As with the basic actions, not every quick bet option will be visible in every situation. The different quick bet buttons are explained below:
You can also click somewhere on the slider bar or click and drag the slider bar to adjust the Raise To amount you'd like to bet. The further right you drag the slider bar, the higher the amount displayed, and the further left you drag the slider bar, the lower the amount displayed. Once you have the amount you'd like to bet, simply click the 'Raise To' or 'All In' button to apply the bet.
Finally, you can click directly in the text box above 'Raise To' or 'All In' and type the specific amount you'd like to bet in that box. Once you've entered the amount you wish to bet, click the 'Raise To' or 'All In' button to apply the bet.