XML : Returns "System.Collections.Generic.List" instead of recordset in XML or JSON

I have a table of employees that I am wanting to return all to the browser in XML. I have followed the tutorial here "http://csharp-video-tutorials.blogspot.com/2016/09/aspnet-web-api-and-sql-server.html" and did this in the same way. However, when I run this I do not get the list in XML at all.

I put this into the browser address bar: Employee/GetAll

  {CONTROLLER CODE}  // GET: ALL Employee  public List<DimEmployee> GetAll()      {         using (AdventureWorks_MBDEV_DW2008Entities entities = new      AdventureWorks_MBDEV_DW2008Entities())          {              return entities.DimEmployees.ToList();          }      }    

I get this returned in the browser window instead of XML or JSON: System.Collections.Generic.List`1[AdventureWorksDataAccess.DimEmployee]

I have seen two tutorials where this returns XML but for some reason not for me. I am using MVC5 Web API; can anyone tell me why this isn't working?

Thanks.