American Airlines Bradley Airport Terminal operates out in terminal A in Windsor Locks, Connecticut. Terminal A at BDL is also known as the "Bradley Terminal" and is home to other airlines as well.
To reach Terminal A at BDL, you can follow signs for "Airline Ticketing/Check-In" or "Terminal A" once you enter the airport. If you are dropping off a rental car, there is a rental car return area located on the ground level of Terminal A. Once inside the terminal, you will find American Airlines' check-in counters, security checkpoints, and gates.
It's always a good idea to check your flight information with American Airlines before heading to the airport to ensure there haven't been any last-minute changes to your flight's terminal or gate assignment.