How to make a sliding undeground staircase that is easy in minecraft?

I have a house in minecraft that I have a vault in on the main floor and i want to make a sliding staircase in that goes underground into my vault. I want it to be 2 wide or whatever and easy. Please help me, I looked all over youtube and the videos were no help

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Tenes que abrir el baul y en donde esta todo de las puertas va a haber una escalera, no parece una, pero lo es
es marron

milagros