Everyone gets 2 cards, then there is the first round of betting. Then the flop is dealt – 3 cards face-up. Another round of betting, then the run is dealt – another card face-up. A third round of betting, and then the river is dealt – the final face-up card. In between the flop, run, and river, the dealer will burn a card to prevent cheating. So you have the two in your hand, plus the five up on the table to make a hand. If everyone else folds, the remaining player doesn’t have to show her hand, but if there is a showdown then everyone of course must show. Split pots can happen, and often it takes a few minutes to figure out who can make the best hand at the end of it all. There are also rules about how much to put in the pot at the beginning, depending on where you sit relative to the dealer – the big blind and the little blind. Wikipedia can give you more details.