Just came across your mod but how do I install this server side the docs say you can do but theres no instructions on how to.

You will need the Fabric Loader, gotten at https://fabricmc.net/use/.
Installation instructions are on that same page.
Then, once you have installed Fabric, you can simply put Lithium in the mods folder that is generated.

Cheers didn't know what fabric was, cheers

Lithium is installed like any other Fabric mod... we don't have special installations instructions. I can add a link to Fabric's installation page on CurseForge, but I can't provide support for installing Fabric itself.