To be able to add mods to the server you would need a jar that is compatible such as Forge, Fabric or Mohist.
Mohist supports both forge mods and plugins. Some mods might not be fully compatible with Mohist and some might break your server entirely (BE CAREFUL AND ALWAYS BACKUP).
- Get a Forge, Fabric or Mohist server
- Start the server to generate the files/folders
- Go to curseforge website to download the mods here (Please download mods that have the same version as your server)
- Go to File manager -> WebFTP.
- Upload the server mods to the
/modsfolder via WebFTP or FileZilla (If you do not have a mods folder create it)
- Restart the server
- Install the Forge/Fabric client same as your server version using the Forge installer here or Fabric installer here
- Once you install the Forge/Fabric client, open up Minecraft and you will have a new Forge/Fabric version you have installed
- Add the client mods to the
.minecraft/modsfolder in your local game
- Select the new Forge/Fabric version that was installed on the Minecraft launcher and press play