Realtime Script Compiler (Lua, JavaScript, C#)

I need a way of compiling player made code and run it in game. I have looked at lua Interface and kopiLua and I have no idea how they work. Im using Unity free and developing for Windows PC. It doesn't have to be lua, but it has to be compiled at runtime.

Just so you know, I have no idea what the githubs on kopiLua mean...