The above answers are correct, but I'm afraid your question may not be completely answered.

If you do not currently have Cable or DSL, then you are not prepared for wireless. The first step, for your home, would be to get cable or DSL. Then if you still want to go wireless, use SleepR's advice.

Adding the PCMCIA / PC Card or a USB adapter is useless for you currently, as you have nothing to connect to (unless you go to StarBuck's, etc).