Terraria How to Add new Server Mods with tModLoader.
Stop your Game Server
Click on Mod Manager Icon then install tModLoader
With tModLoader you can add hundred of Mods, such as thorium.
I'd recommend that you read some guide on how to use tModLoader.
You need tModLoader on your computer (and everyone that want to play on your server)
On your computer, add the mod that you want to use and save.
Locate the mods file on your computer, by default it should be something like : C:\Users\yourUser\Documents\My Games\Terraria\ModLoader\Mods\
Upload all the .enabled and .tmod file to your server in the folder gamehosting_saves\ModLoader\Mods\
Make sure that the .enabled file content is "true" and not "false" or empty. Otherwise it will not activate the mod
Start the server again :)