well, first excuse my expressions

but at the beginning i provided you with the uberuseful blender wiki, a short look for rig might give you a starting point

I am by far not an advanced animator.
The rig is the skeleton you see, the sum of the bones which belong to each other. So, in a way, the animation is done by transforming the rig, the bones.
In the nif, each dummy has a set of bones asigned. which suggests, that each bison needs to be assigned to an individual set of bones. but as I see it, in blender everything is aligned over each other, all in the same place.
why did you cut in the eye holes in the first place? having them stay where they are would make your life easier. right now I found one eye inside his head, turn on wireframe and have a look inside his head

either you delete this fragment or you move it to where it belongs and then weight paint it to the head.
ok, let me know if you can progress

I hope at the end of all this, you will have a lot of experience
