differential problem

[3dson]

Hello. Well before i start im kind of new with differential problems. I bought my s14 2 months ago and i had never tried to figure out what kind of differential it had. So i did some research before i posted this topic and i found out about Open Diff and LSD diff. I checked 2 see what kind of diff. i have on my car but once i spin the rear wheel the other one was motionless. So i dont know if the diff. might be broken or it might have the wrong fluid in there. Some of my friends told me that the diff might be a VLSD but im not sure so my question to you guys is should i replace the differential or is there something else i ca do.

-Ed (sorry for this novice question)