Questions on Great Expectations

I was really confused about what was going on before and during Mrs. Joe's funeral in chapter 35. At the bottom of page 281 it says, "The remains of my poor sister had been brought round by the kitchen door, and it being a point of undertaking ceremony that the six bearers must be stifled and blinded under a horrible black velvet housing with a white border, the whole thing like a blind monster with twelve human legs, shuffling and blundering along under guidance."

I don't really understand what he's talking about right now or why Mr. Trabb is in control of the funeral proceedings. From pages 280 to 282 in which the funeral is described, I was lost as to what was happening. My feeling is that I'm missing some reference to how funerals were done at the time this was written. Perhaps some serious background knowledge of mourning procedure would be helpful.