hello, I'm trying to install a mod on the server but I don't know where to move the mod files. The organization of the online server is different from my hard drive, help me

Yep, it'll be slightly different, and you'll have to create the "Mods" folder while in the FTP program of your choice.

The directions on the URL below are what's recommended for installing Modlets / Mods, and you'll need -some- basic computer knowledge on how to navigate program files.

https://7daystodie.gamepedia.com/HowtoInstall_Modlets