Code
using System;
using System.Collections.Generic;
using System.Text;

namespace ConsoleApplication3 {
    class Program {
        static void Main(string[] args) {
            List<OP> table = new List<OP>();
            OP o = new OP(DateTime.Now);
            table.Add(o);
            o = new OP(DateTime.Now.AddDays(-1));
            table.Add(o);
            o = new OP(DateTime.Now.AddDays(1));
            table.Add(o);
            foreach (OP op in table) {
                Console.WriteLine(op.ToString());
            }
            Console.WriteLine("----------------------");
            table.Sort(new Comparison<OP>(delegate(OP a1, OP a2) {
                return DateTime.Compare(a1.Modified, a2.Modified);
            }));

            foreach (OP op in table) {
                Console.WriteLine(op.ToString());
            }
            Console.ReadLine();
        }
    }

    public class OP {
        public OP(DateTime _modified) { this._modified = _modified; }

        private string _name;
        private DateTime _modified;

        public DateTime Modified {
            get { return _modified; }
            set { _modified = value; }
        }

        public string Name {
            get { return _name; }
            set { _name = value; }
        }
        public override string ToString() {
            return this.Modified.ToString();
        }
    }
}