To be precise:
* You'll need to consult a repair manual specific to your engine's displacement (5.4L or 6.8L). These manuals will have diagrams showing the exact plug locations and the proper firing order. A Haynes or Chilton manual is a good place to start.
* Your truck's owner's manual might have a simplified diagram, though likely won't show the exact plug locations in as much detail.
Approaching the plugs without a proper guide risks damaging something. Don't attempt this repair if you're not comfortable working on vehicles. A small mistake could lead to serious damage to your engine.