The best way to learn the game of poker is to start playing. Try Zynga Poker or any other site. If you need some inspiration, check out Charlie Nesson on The Colbert Report to learn more about the value of learning to play poker.
If an online game is too much of a first effort, you can simply play "War!" With the option to fold or go "all in" with your bets before flipping each card. That exercise with one card (then with two cards) is meant to help novices develop a comfort level with betting and the emotions that go along with it.