Hello! I couldnt find a thread on how to start making Rust plugins? Can someone help me out?

You can find thread only if you use search, there are plenty of them. 
Get familiar with c#, look into game dlls and existing plugins. 

Actually right here n umod they provide you with alot of tools to get started, hooks for scripts and plenty of really good free info.

Wulf and his team are awesome people.