First, catch some trout.
Coat the outside very lightly with oil.
Sprinkle Old Bay Seasoning inside and out. You'll have to experiment to your taste. If you're doing it for the first time, you might do one fish lightly, another a little heavier and another even heavier, if you catch that many fish.
Wrap each fish in its own foil packet.
Put the foil packets on coals (not in the middle of a bonfire) and let them cook for a few minutes on each side, depending on how hot the coals are.
Take a peek at one, and if it's done, ring the dinner bell.