hrmm.. your best bet is to consult a rulebook, but I can give you a general idea. You make a deck of 60 cards. You need a decent number of Basic pokemon (You have to play a basic pokemon before you can use it's evolved form) as well as plenty of energy cards that match the requirements on your card's attack. You can also use some trainer cards which do things like heal your pokemon or search your deck for certain cards...
On your turn you put pokemon cards into play, attach energy cards to them, etc. and you also make attacks on your opponent's pokemon. When you've defeated around... 6 I think, You win (It's beeen a LOOOONG time since I've actually played) If you have any more in depth questions I can try to answer them... jsut post them here.
JOIN AN RP YOU SLACKERS!