Just to expand on what Vic said, there are some great books you should read. Super System, and Harrington on Holdem books are pretty much essential reading for any aspiring poker player. My adivce is to play hands, play hands, and play even more hands because reading will only get you so far.
As far as playing, to start out just go to some freerolls
and use it to hone your skills on how "you" want to play your hands. Note: 99% of the time the freerolls is not what you will see in real poker. Then slowly move up when you think you got a good grasp to build a bankroll. Dont go up to far though or one bad beat will send you back down to the bottom.
Finally, get feedback on hands you think you played well, you think you played wrong, and you arent sure on. Like Vic said you could have days where you play very well and get crappy results, or you play crappy and get every miracle card you can think of (just ask Jamie Gold when he won the WSOP
). Now the key is to win the battle of mistakes because everyone makes them...well except Phil Hellmuth. Now in the case of having a bad streak, just take a few days off to regroup for a few days and you should be fine
Hope this helps your game and good luck at the tables.