Installing mods is very easy:
1. Download the mod you would like
2. You (normally) don't need to unzip them! (Unzipping is optional since v0.10!)
3. Copy the mod into your servers mods directory. If the directory doesn't exist, create it.
4. Run the game (You also need to have the mods on your client end as well)
5. Open the Mods menu and make sure the mod is enabled (requires restart on changes)
Enjoy your installed mod.
You can find new mods here https://forums.factorio.com/viewforum.php?f=14
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