I'm not that familiar with the airport itself as I haven't really paid attention to details when I've arrived there, but after a bit of looking around, I did find a
website for the airport as well as information for arrivals. You will have to go through passport control, get your bags, and then go through customs. Then, you could wait in the arrivals hall for your friend (or vice versa, depending on who arrives first).
It looks as though American Airlines arrives in Terminal A; I don't see US Air on this list, so I'm guessing it's a codeshare flight with another airline in the Star Alliance such as Spanair or Lufthansa. If you are going to be landing in different terminals, then you should decide which one you want to meet in. And, you should obviously have each other's flight information so that you can check the display monitors in case there is a delay of one or both of the flights.
You can see more information, and click on maps of the arrivals halls,
here. It looks like there are three places to eat in Terminal B and one place in Terminal A, so you might choose one of those as your meeting spot.
Good luck!