I would personally break the doll apart into its components and cleanse the pieces individually. If you have anything involved that is safely biodegradable then burying the pieces is a nice touch, if you have anything you want to re-use then given a good cleanse they should be fine to use again.
I personally find that the breaking apart of the poppet breaks the connection, the cleansing simply ensures there is no remaining energy.
A poppet is used most often for what is called sympathetic magic. That is, the poppet, or doll, is a representative of the target of the work. In some cases, someone may make a poppet to represent another person. In some cases, a poppet may represent one's self.
A very simple poppet is made by cutting two pieces of fabric into the rough shape of a person (think gingerbread man shaped). The edges are sewn together, with enough allowance to stuff the doll. Whether it it turned inside-out is up the the practitioner, but I digress.
Whether the doll is stuffed with fluff is a matter of opinion or whim. In many cases the person doing the work will include either personal tokens, such as hair, a scrap of the person's clothes, a photograph, the person's name written on paper, and as much as can be associated with the target of the work, inside the doll. Then the doll is sewn shut. The full intent when gathering and creating what goes inside, and the full intent while creating the poppet, is focused on associating the device with the target such that there is an almost Pavlovian connection in the mind of the maker.
As for use, they can be used to bless, used for protection work, to filter, to curse, to send ill-will, or the like.
Sympathetic magic can be as simple as drawing a representation of the target on paper. A poppet is not an absolute necessity, though the creation process can make the work much more effective.
Also, some people will make a (semi-)permanent poppet for some purposes, or a temporary poppet for specific purposes.
One member here on SoM has mentioned making a poppet from wood, and using a pouch for the associating items. The process of creation is up the the creator, in my opinion.
A little bit of a side note: Poppets are the origin of so-called Voodoo dolls. The idea has been severely romanticized in literature, and other wild tales told about things which people may not understand directly.
What prsona said. I also want to add something my poppet I used a colored cloth to represent my birth sign and one of my old shirts also color magic. If you can't use cloth you can use anything for your poppet even eat able things like corn. You can use a poppet for anything.