From the front of the Transport the distributorless ignition pack is at the lower left. To the right, closest to the ignition pack is cylinder #1, then #3, then #5. Opposite #1 is #2 then right to #4, then #6. The firing order is 1-6-4-5-3-2.
The firing order for the 2002 Pontiac Firebird 3.8 liter FI OHV 6-cylinder is 165432. You can view a diagram of the firing order on the AutoZone website. Select your make and model, and click on Repair Help.