To play online casino slots, start by choosing a reputable online casino and creating an account. Once you've signed up, deposit money into your account using your preferred payment method. Next, browse through the available slot games and select one that interests you. Set your bet amount and the number of pay lines you want to play, then click the "spin" button to start the game. If you land on matching symbols according to the game’s rules, you win, and your winnings will be automatically added to your account.