M9K Sound Modification

Alright so I’m fairly new to modding and I would like to make a sound-pack for the Muderthon9000 weapons addon (I want to make the guns sound more threatening- think the bank shoot-out from the movie HEAT) how would I go about doing that? I have all the sounds I intend to use but I have never made a sound pack before or messed around with someone else’s addon. I know it might be simple for a lot of you but I’m not really one to mess around with other people’s things.