Summarize:

You need a minimum of two people to play Chopsticks but there is opportunity later to add more opponents. Each time you start a round of the game you both hold your hands out with one finger extended. Make sure that both you and your partner keep both hands flat and straight out so that both of you can see how many fingers each person has extended throughout the rest of the game. You will then take turns going back and forth. On each turn, one player will use one hand to tap one of their opponent's hand. Let's assume you are going first. If you tap with one finger then your opponent will add your one finger + their extended fingers and extend the sum of the two. For example, you tap your opponent's hand. You have one finger and they have two. They then add the fingers and on their tapped hand, they put out three fingers. On the next turn, your opponent uses their hand of three fingers to tap your hand of one. You now have to hold out four fingers because your one finger plus their three equals four fingers. Only the tapping hand has the power to change your opponent's hand. The goal is to keep going and adding fingers to your opponent's hand by tapping. When someone's hand reaches five fingers that are extended, that hand is considered "dead" and is no longer in play. There are several variations of this rule, but the simple rules of Chopsticks dictate that once a hand has reached five fingers, that hand is useless. Which makes sense because one of background stories behind Chopsticks is that you can hold a chopstick with up to one finger, but an open hand means that you are going to drop your utensil and food as well. Continue playing until one player has lost both of their hands. The goal is to be the last one standing with at least one hand left still alive. Like many math and strategy games such as chess, there are a limited amount of plays that are possible before the game becomes predictable. To prevent the same player winning every round and the other player losing, add the other rules to make the game play fair.
Start with two players. Face your opponent as you both put your hands in front of you. Pick one person to go first. Tap one of your opponent's hand with one of yours. Take turns between players to tap each others' hands. Hide dead hands behind your back. Master the basics and then add new rules.