Switching .Rez files

Okay so I am learning how to mod and I've done a couple Simple ones (changing colors, adding patterns, etc) and I'm trying to figure out how to switch an entire weapon with another (so I can do superknife). How do you switch m9 or m16 with minigun?

I don't know my self but search it in the search bar in the forum .. It might be able to find one for you