MR LAX
Sorry, I'm a bit puzzles here because a briefing is more than just getting an instruction.  If you were instructed, the simple words are: "I was instructed".  If: "I was briefed", to brief means to have things explained to you and set out, what the plan might be, what the objective might be, that's what a briefing is and that's the word that is used here, so please explain this to us.