Almost all of FR's departures are from gates 1-3, and FR have that area of the departure lounge decked out in their colours. When you pass through security, keep walking through the 'new' departure lounge, and go round the walkway virtually as far as you can (a 5-10 minute walk). This is in fact the old departure lounge, and has its own eaterie.
You will then be close to the gate for when the flight is called.