While we cannot help you with passwords per forum rules, I hope that's not what you are having issues with.
You have a macbook / powermac G3 with an airport wifi card. Do you have an internet connection and wireless router? If so just follow these instructions to correctly setup your mac to access your router.
http://support.apple.com/kb/HT1126
If you are trying to log into some random person's wifi don't bother replying to this thread or coming back here. This place is for white hat's only.