StructureMap example...

StructureMap.cs

var container = new Container();

container.Configure(configurer =>
{
  configurer.For<IUsersRepository>().Use<SqlServerUsersRepository>();
  configurer.For<IPostsRepository>().Use<SqlServerPostsRepository>();
});

var usersRepository = container.GetInstance<IUsersRepository>();

var users = usersRepository.FindAll();

foreach (var user in users)
{
  Console.WriteLine("Username: {0}", user.Username)
}