If you are holding a hand that has a low card value, you have several choices for betting. You can fold or check, and if you are missing a card, you can bluff. Depending on the amount of money you are willing to bet, you can even win the game with a bad hand with the right skills and luck. Likewise, if you have a strong hand, you can bet in order to force weaker hands to fold or to raise the pot value.
Poker is a game of chance, but with betting, the game gains psychology and skill. While this is a basic primer, you can find much more detailed information in books on poker. Of course, playing in a poker tournament or with a group of friends is more effective than studying the game in a book.
In order to improve your poker skills, you should watch others play and develop quick instincts. While watching, observe the way they play, imagine yourself in their shoes, and then think about how you would react in the same situation. Then, figure out how you could improve your strategy based on this. For example, before starting a new game, shuffle the cards several times to get a feel for how they handle various situations.
The best poker hand is the royal flush. A royal flush is a hand of five cards of the same suit. If you have two four of a kind, the higher-rank card wins. Similarly, if you have four of a kind but one of them is lower, you have a flush.