Dependencies for mod

So, I've got an idea for a mod. I know C#. I've been running a modded Rust server. I've got VS installed, booted it up, and went about trying to start writing a script for said mod. I realized I have no idea what I need to add to my project as a dependency so that VS recognizes some of the API calls I'm trying to make. Is there a specific dll I need to add?

 

you should add the Assembly-Csharp.dll from your server.

 

Thank you.