WCFD数据.Service1不实现接口成员

我正在使用visual studio 2010遵循关于C#上WCF的指南。我以为我做的每件事都是正确的，直到我建立了解决方案，我遇到了这个错误。有人能告诉我该怎么做以及如何修复它吗？为什么会发生这种情况？我对这件事还很陌生，所以任何帮助都会非常重要。

这是我的密码。错误出现在Service1 : IService1中的第一行。我确实看到了纸条，但我试着把service1改为说"你好"，但没有成功。

namespace WCFData
{
    // NOTE: You can use the "Rename" command on the "Refactor" menu
    // to change the class name "Service1" in both code
    // and config file together.
    public class Service1 : IService1
    {
        SqlConnection conn;
        SqlCommand comm;
        SqlConnectionStringBuilder connStringBuilder;
        void ConnectToDB()
        {
            connStringBuilder = new SqlConnectionStringBuilder();
            connStringBuilder.DataSource = "NATHAN-PC''SQLEXPRESS";
            connStringBuilder.InitialCatalog = "WCF";
            connStringBuilder.Encrypt = true;
            connStringBuilder.TrustServerCertificate = true;
            connStringBuilder.ConnectTimeout = 30;
            connStringBuilder.MultipleActiveResultSets = true;
            connStringBuilder.IntegratedSecurity = true;
            conn = new SqlConnection(connStringBuilder.ToString());
            conn = conn.CreateCommand();

        }
        public string GetData(int value)
        {
            return string.Format("You entered: {0}", value);
        }
        public CompositeType GetDataUsingDataContract(CompositeType composite)
        {
            if (composite == null)
            {
                throw new ArgumentNullException("composite");
            }
            if (composite.BoolValue)
            {
                composite.StringValue += "Suffix";
            }
            return composite;
        }
        public int InsertPerson(Person p)
        {
            try
            {
                comm.CommandText = "INSERT INTO Person Values(@Id, @Name, @age)";
                comm.Parameters.AddWithValue("Id", p.Id);
                comm.Parameters.AddWithValue("Name", p.Name);
                comm.Parameters.AddWithValue("Age", p.Age);
                comm.CommandType = CommandType.Text;
                conn.Open();
                return comm.ExecuteNonQuery();

            }
            catch (Exception)
            {
                throw;
            }
            finally
            {
                if (conn != null)
                {
                    conn.Close();
                }
            }
        }
    }
}