This quest begins immediately after you enter the simulator, once it's started you'll be guided down paths on some cliffs and you'll eventually come to a building, work you way through it and don't be worried about getting lost because the whole quest is basically a straight line.
At this point in the quest you actually don't have anything to worry about, along the paths you'll find plenty of ammo/health packs and if you manage to fall off the cliff you'll just be teleport back to it.
Anyway, once you've worked your way through the building mentioned above, you'll come to another cliff edge with 3 mounted guns, you have to place explosives on them and then vacate the area!
Continue you to follow the path and do the same to the other guns as you come across them, once you've done them all you'll be teleported to another area which will signify the quest being complete and the achievement unlocked!
If you're getting a little lost or just confused by my directions, try checking out the video guide below!
*Credit to MahaloVideoGames for the videos