As the name suggests, poker is a card game that involves betting. It is played between two players and the rules of each variation determine how many cards are dealt and how the betting process works. When playing poker, players must remember that the game has a short term luck element to it and that you will lose from time to time.
When the cards are dealt, players can decide to check (passing on putting chips into the pot) or call, which means placing chips in the pot that match the bet made by the player before them. If a player wants to place more chips into the pot than their opponent did, they can raise.
Whether you are holding a strong pocket pair of AKs or a speculative hand that has potential after the flop, you want to bet aggressively to get value for your money. Many novices tend to be too passive and limp into a pot when they should be raising. This is a big mistake because it can cause you to miss out on the value of your hand when it hits the board.
Read as much as you can on the game and try to develop good instincts. It is also a good idea to watch other players play so that you can pick up on their tendencies. Keep a journal of what you learn so that you can refer back to it later.