Poker is a card game with hundreds of variations. However there are some basic rules that are universal to all games. For example, players must always ante up some money to be dealt cards. Each betting interval is called a round. Players either call a bet by putting into the pot the same number of chips as the player to their left, raise if they are ahead in their chip count or drop (fold). A player who drops forfeits any chips that they have put into the pot and is out of the hand until the next deal.
When a player has a strong hand it is important to play that hand aggressively. This way you can build the pot, scare off other players who might be holding draws and increase your chances of winning the hand.
A good poker player will also learn how to play different hands and understand the strengths of each. They will know that a full house beats a flush, three of a kind beats two pair and so on.
When learning poker it is best to start at the lowest stakes. This way you can play versus weak players and learn the game without risking too much money. As you progress and get more experience, you can move up in stakes and open up your hand ranges to take advantage of the stronger players.