Best way to add MVC to a Web.api-project

I have an existing web.api-project that i need to add a mvc5 controller/view to.

I tried to add this by hand by adding bits and pieces of folders, references and config-stuff here and there in the project. Clearly i was not successfull because when i try to view my cshtml-files the server just returns server errors. Now i wanna start over in structured manner.

So, with a pure web.api-project at hand, how can i add mvc-support?