How would you connect an antenna to your PC? There is no antenna jack.
Yes, there is, it's just on the inside. Usually, it's a tiny U.FL jack (Google it).
You can buy cheap wi-fi dongles for your USB port on your PC. Very cheap on the Internet. I got one for about $5. You can interface an antenna to the internal antenna on the dongle, so you don’t mess with your PC internals.