how do I navigate in doom?

I just started playing doom 2016 my first doom game ever. im on the 3rd mission/level where I have to find 4 gore nest and I tried for half an hour snd found only 1.. the nav bar on top dosnt help at all.. it tells me to find 3 key cards idk where to find those

ps. the music is easily 10/10 .. mick Gordon is really good with thr 9 string