program.cs

using System;
using System.Collections.Generic;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            var user1 = new User();
            user1.Username = "gigi";
            user1.Password = "gigieparola";
            user1.Email = "gigi@gmail.com";
            user1.Age = 20;

            var user2 = new User("Andrei", "parolamea", "email_andrei@gmail.com", 12);
            var user3 = new User("Alex", "123456", "email_Alex@gmail.com", 22);
            var user4 = new User("Dana", "BigPassword", "dana123@gmail.com", 19);
            var user5 = new User("Alexandra", "BuildFailed", "alexandraaa@gmail.com", 18);

            var userList = new List<User>();
            userList.Add(user1);
            userList.Add(user2);
            userList.Add(user3);
            userList.Add(user4);
            userList.Add(user5);

            var userService = new UserService(userList);

            // afisam toti userii
            foreach (var user in userList)
            {
                Console.WriteLine(user.Username);
            }
        }
    }
}