How to populate longlist using WCF service

See more:

SQL

WCF

LINQ

C#5.0

VS2012

I want to populate longlist on my WP 8 page via WCF service. I'm following this tutorial but get errors. Here is my service implementation:

private static IEnumerable<worker> GetStuffList()  {
            List<worker> stuffList = new List<worker>();
 stuffList.Add(new worker() { Name = "John", Age = 23, Sex = true }); //error 1
            return stuffList;     }
        private List<Group<worker>> GetStuffList() // error 2
        {            IEnumerable<worker> stuffList = GetStuffList(); // error 3
            return GetItemGroups(stuffList, c => c.Age.ToString());  }

        private static List<Group<T>> GetItemGroups<T>(IEnumerable<T> itemList, Func<T, string> getKeyFunc)
        {
            IEnumerable<Group<T>> groupList = from item in itemList
                                              group item by getKeyFunc(item) into g
                                              orderby g.Key
                                              select new Group<T>(g.Key, g);
            return groupList.ToList();
        }
        public class Group<T> : List<T>
        {
            public Group(string name, IEnumerable<T> items)
                : base(items)
            {
                this.Title = name;
            }
            public string Title
            {
                get;
                set;
            }   }
        public class worker
        {
            public string Name;
            public int Age;
            public bool Sex;
            public worker(string Name, int Age, bool Sex)
            {
                this.Age = Age;
                this.Name = Name;
                this.Sex = Sex;
            }
        }  

Errors:
1) 'WcfService1.Service1.worker' does not contain a constructor that takes 0 arguments.
2) Type 'WcfService1.Service1'; already defines a member called 'GetStuffList' with the same parameter types.
3) The call is ambiguous between the following methods or properties: 'WcfService1.Service1.GetStuffList()' and 'WcfService1.Service1.GetStuffList()'

Could you correct my code please.