A lot will depend on what you ordered. If it is a tanned and dyed skin, then use it like any other leather. If it is same' (rawhide stingray skin), it will be white and rock hard. After cutting out the piece you are going to use, you will soak it in warn (not hot) water until it is soft and pliable. Wrap it around the handle, overlapping the edges, and mold it with your bare hands. Once it is in place and worked into shape, wrap it tight with string/ flat rubber strip/shipping tape/whatever to hold it tightly in place until dry. It will be hard again when dry.Moisten the area where it overlaps to soften it, and cut through both layers with a thin sharp blade.Now you have a fitted handle wrap.Trim as needed, and apply white glue or Tightbond to the handle and stingray. Put on and wrap again until dry. Clean up any squeeze out, and proceed as desired.
Same' can be painted with lacquer and then sanded to show the bumps. A coat of some sort of sealer/lacquer/etc. is needed if the same' will be exposed. If you are doing tsuka-make, you don't need to coat the same', unless you want to color it.
There are few handle materials that rival stingray for beauty and durability.
Stacy