This part of the Fallout 76 Walkthrough reveals the complete unfolding of the main quest I am the death.
In the Whitespring Bunker, enter the command center (picture1). Launch the 4 tutorials to know the steps allowing you to launch a nuclear warhead on Appalachia (pictures2and3).
Take an interest in the map to locate the Appalachian breaches (picture4). By interacting with each point, your map updates (picture5).
Then speak with MODUS (picture6). Now that you know the theory of nuclear missiles, you can move on to practice. Use the surveillance system terminal (picture7), then select the first entry concerning the nuclear access card (picture8): the main quest Hide-seek-destruction begins.
After recovering the nuclear access card and the 8 code fragments from the Alpha, Bravo or Charlie silo, consult the archives terminal in the bunker (picture9). Select "Data Archive", then "Archive: Ellen Santiago", and finally "Code Fragments": you get the Fujiniya Center password.
Then go to the Mama Dolce Food Processing Plant (picture10). Enter the pipe outside the building using the hatch (picture11), then open the secure door with the badge (picture12): you can enter the Fujiniya intelligence base.
Progress in the area until you find a terminal, use the password (picture13), then select the last line (picture14).
To complete this quest, you must complete the Mission: Alpha/Bravo/Charlie Countdown side quest.