Ps3 online question?

May be...

how do you buy games or whatever, is it by credit card?

Yes you can set it up via credit card or you can buy one of the gamecard. It's not available in North America yet..hopefully soon...I like to use those instead of my credit card.

Yes it is by credit card and that's the only way to get the games. You can just goto the PS3 store and simply get a game title. Which, only a few of the PS3 game titles are buyable in the PS3 store.