how to edit multiple sprites together

I have a very simple question, how do I, when I edit a 16x16 block all the others are edited too?

You’re obviously doing tiles, which is why we have Tiled Mode (or whatever it’s called) as simply explained here.
It is true though that Aseprite really needs something like objects with multiple instances, similar to Flash’s Objects

As @Glitcher said, for a 9x9 grid of the same tile, you can use View > Tiled Mode > Tiled in Both Axes. There are plans for a tile map editor.