hi mate
i know everything is a little overwhelming just now,...i was you a couple of years ago!!!
look here
http://www.subsim.com/radioroom/showthread.php?t=96026
it should give you plenty of info
dont worry , the more others that read this post, the more help you will get.
take one thing at a time, and your sh3 game will look like nothing you could imagine!!!.
don't go d/l every mod just now...as a lot are already in gwx3.0 (gold)
familiarise yourself first!!!
jsgme and commander info is in the thread above