How do you get the Crusher skin in JPOG PC

first you have to have winrar and then you download the skin and extract the files to C:\Program Files (x86)\Universal Interactive\Blue Tongue Software\Jurassic Park Operation Genesis\JPOG\Data\matlibs some Jurassic park sites where you can find skins are
http://modgenesis.hostingdelivered.com/index.php
http://rpgtopia.com/
http://www.jplegacy.org/home.php

If you're looking for the Crusher skin, specifically, go to RPGTopia. That is where the skin creators are based, and where you're most likely to find support for it.