How to add mods to a modpack?

[NarutoSasukeRasen]

I have the folder and everything but if I put it in the mod folder or if I put a coremod will everything still work or will go bad?

[theprolo]

That depends entirely on the mod, the Minecraft version, the mod's Minecraft version, and in some cases the other mods. You can't just make a blanket statement about this with so little detail about what it is you're doing. If you want a more definitive answer, you need to tell us all of the details I just mentioned.

[dwwojcik]

Nods go in the mod folder, and Coremods go in the coremods folder. Simple as that.