Head to graveyard near of any major city of your faction and /dance with Catrina to get one from easiest achievements ever. Also do not forget to talk with vendor (available at the same place) and get Boquet of Orange Marigolds - it will allow you to see departed (ghosts of dead people, what else).

But, that's not all, purchase recipe for Bread of the Dead (Ice Cold Milk and Simple Flour needed, so buy it straight as you have too cook it at "Ghostly Cooking Fire" anyway) - you will need it to feed the ghosts. And worth to say, it's another recipe if you hunt cooking achievements.

Anyway, if you see the ghosts, you can get quest Cheerful Human Spirit - after completing you can get Macabre Marionette pet (usable only during the event and it's not regular pet which you can learn as others).

Are you unable to get that quest? Well, it's simple, you have to be in graveyard of your (race) major city. The rest can be done on any graveyard of your faction. Or, if you are extremely lazy, Dalara is the key :)

And that's all folks.