I had always thought that how Sherlock faked his death was a bit of mystery, as Sherlock himself never told anyone how he did it. However, my friend is convinced that Sherlock faked his death exactly how Anderson theorized it. Sherlock never responds to Anderson's theory, so I assumed this was because he had got it wrong. Did I understand incorrectly? Did Anderson actually get the theory right?
The answer is: kinda.
In the first episode of Season 3, we see Sherlock sitting with Anderson after supposedly explaining how he did it. It's left up to viewer interpretation if this scene actually occurred and whether the explanation offered was real or not, because Sherlock disappears from the room and we see Anderson have a bit of a mental break.
They never explained it.
You haven't missed anything.
Although many theories were posited, and Sherlock himself gave Anderson a version, none of the explanations fully matched the events.
Further, neither Moffat nor Gatiss have officially revealed how it was done, despite claiming they have a workable solution.
To date, there is no official explanation as to how Sherlock faked his death.
There were a number of possiblities that could have happened on the roof top each one had a codename. when moriarty killed himself sherlock initiated one. he then fell and landed on a blowup thing. molly then threw a body out the window so john and the snipers would see a body fall. a biker then bumped into john so they had enough time for sherlock to go on the floor and lie down( because the body didnt look exactly like sherlock) they then placed something on sherlock so his pulse stopped and poured fake(or real) blood on sherlock so he looked dead. they loaded him onto the ambulance and took him away. He then broke up moriartys network of criminals.