How to replace weapon models in mod

[Kato]

Hi, I've recently begun creating a mod (an ambitious project, I know) and have modelled my first weapon, a crowbar replacement. I haven't begun animating it or anything yet (don't know how at the moment, this whole thing confuses me), but I would like to know, how can I replace the crowbar in my mod with it? I've read about things that involve GCF files and stuff but my mod doesn't have a GCF to replace...lol...

So, please help me if you can.

-Kato