sigh* first of all, I have no idea what your talking about.
But from what Ive gathered:
to check if you have air port: HD/applications/utilities/AirPort Admin Utility/if nothing shows up, press rescan, if still nothing shows up, you have no AirPort.
In the case you have AirPort, and somehow someone really dumb set up a wireless network near you and didn't put any admin controls on it, that would be how you are connected when you are nowhere near the internet hardwire.
(how do you not know if you bought an AirPort?)
2nd:
From that unpluged cable from the wall bit..:
ok, now you have a cable connection. If you plug one line into the wall, one line into the cable modem, and one line into the computer so all 3 are connected to eachother directly or indirectly, then you have an internet connection (assuming you have that ability) If any of those lines are disconnected, you no longer have Internet, you may have ethernet connection if other computers are connected, but you would not beable to access this webpage. The only way you would beable to view any webpages is if your using a browser that has the ability to save entire webpages (like iCab) but your not viewing it in real time, any refresh will erase that info.
If that didn't answer your problems, we need more information.