What folder structure for the dll project in .NET framework I'm going to play in the main project

I have a vs2017 solution with a main project that will use a dll project as a reference.

I created the model, business and repository folders in the dll project Main project use the dll in the main class.

What goes into each folder in the dll?

model
 -Pessoa
 -Ipessoa
Negocio
 ? - Preciso deste??
 ?
Repositorio
 -Repositorio - class
 -IRepositorio - interface

I can use it normally, but what do I lack to use the business folder?

Create a soh class to make it available? Or use the direct repository?