I'm confused about modding in custom servers. And I need help

I downloaded few mods to my custom server and it appears that some of them work but anything that has any items doesn't work. I can't see any new items spawning around after a great while. How can I get items spawn or what should I exactly do to get mods working properly. I know every mod doesn't work but these were super popular and said they should work with newest version. So I really need help. I don't know shit about mods here. My experience is from downloading mods to arma 3 so it's quite different still. If someone can explain this like im 5 it would help