I'm replacing my old tailgate, but the new one is just the shell. I want to know how to remove the handle and all the hardware from the old one and put it into the new one.

 

It's fairly easy.
Remove the 2 plastic rod retainers from the latch/rods.
Remove the 3 bolts form the inside tailgate.
Remove 2 bolts on each latch. Support the tailgate with a box or something when you remove the cables from the latch bolts.

I would go ahead and get new rod retainers.