What special training do you take to learn how to twist a person's neck to die?

Nah.  That wouldn't work in real life.  It's not that breaking a neck is impossible so much as that you'd NEVER successfully pull it off against someone resisting and the instant you put your hands around someone to do it, they'd naturally recoil and stiffen up...which would engage the muscles that would make it so you wouldn't be able to snap their neck.

Sometimes Hollywood just makes sht up.

Little more precise then what one see's in the movies and such, proper leverage and such can be efficiently and effectively taught by trained personal though.

None, just use your pure strength. Just don't do it or you will be in prison, nothing fun to your mental health because you get an hour of sunlight a day and locked up in a box for the other 23 hours

There is probably an instruction video on You Tube .

Yeah, they give you that at police stations. Walk right in and shout "how do I break someone's neck so they die?" really loudly, then leave before they notice.