Starting my very first FF6 hack and had some basic questions.

Alright, I'm not quite wrapping my head around the B2 command. I get that it pulls a subroutine from another part of the game, but I'm not quite grasping how you determine where it's coming from. How does 00 00 31 translate to FB/0000? I'm also finding myself nervous to really start anywhere. I'm afraid to just go thrashing through the hex, because I'm worried that I'll end up breaking something else in the process. My gut tells me to sort of section off a piece of the game, and go from there, but I'm still trying to figure out how everything is arranged. I have a feeling that I'm just making this a bigger problem than it needs to be in my head though. Once I actually DO get started, I think things won't be quite as catastrophic as I'm making it out to be, since I can just change where things point to, and events that get broken can either be fixed, or just point to a different, non-broken event that can be then edited to my whims. Is my thinking on the general right track here, or am I way off?

Edit: On an unrelated note, is Imageshack broken? None of the images in the tutorial are working anymore, and I've seen a couple of threads with busted Imageshack images too. On top of that I logged into Imageshack, and I can't view my own pictures, but I can see their names.