Latitude D531 Can't Connect to Internet

I recently got a Dell Latitude D531 in an auction. The laptop is old, but there's a wifi button up near the power button on the keyboard. When I push that button, the wifi light does not light up, and nothing happens. I have gone into network connections and there is only one connection that shows up, and it is not wireless. I have also tried to connect an ethernet cord directly from my modem, and it doesn't seem to register it. I don't know what to do to get the computer to connect to the internet. Any help would be appreciated!