How do i add weapons to the redead gamemode

I’ve tried countless time’s but i can’t do it. I need help adding weapon’s to a gamemode its in the title its a GMA file format and the creator said there was a lua in the GMA that i needed to edit and i asked him for help and he doesn’t do that kind of stuff anymore. Plz help

You need to extract everything from the GMA

i know but when i add new weapon’s when im in-game i can’t open the shop menu