Build and Shoot

How do I actually put my downloaded .kv6 file into the game? I see a bunch of stuff like casing.kv6, sight1.kv6, sight2.kv6, weapon.kv6, etc. I only downloaded one .kv6 file. So how do I put it into the game? Which file do I replace?

EDIT: I figured out how to do the weapon model itself but how do I convert a .png ironsight/scope into a usable .kv6 file? I can't find any .kv6 downloads for scopes.

there are plenty in the "openspades mods" section. Look at warps stuff. He makes some damn good stuff