Using the mods is very easy:
- Download the mod you would like
- You don't need to unzip them! (Unzipping is optional since v0.10!)
- Upload the mod into your servers mods directory. If the directory doesn't exist, create it.
- Run the game (You also need to have the mods on your client end as well)
- Open the Mods menu and make sure the mod is enabled (requires restart on changes)
Enjoy your installed mod.
You can find mods here: https://mods.factorio.com/