Question: [newbie] Checking if Username is in DB C#.net - WindowsFormsApp, SQLServer

[rsanpedro]

Hello, I'm sorry for posting a question that is most probably very easy for most programmers. I am trying to learn C# and as much as I've googled trying to find the answer, I could not find anything that I understand.

I am aware that there is a login authentication thread in this site for C#. However I am doing the project on a WINDOWS FORM APPLICATION and not a website. And most tutorials I've encountered performs tthe code in ASP.net. Please help me understand. I am using Visual Studio 2008 Express Edition and MS SQL Server 2005.

In so far as I have coded, this is what I have

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.OleDb;

namespace WindowsFormsApplication2
{
    public partial class LOGIN : Form
    {
        public LOGIN()
        {
            InitializeComponent();
        }

        private void Cancel_Btn_Click(object sender, EventArgs e)
        {
            Close();
        }

        private void Login_Btn_Click(object sender, EventArgs e)
        {
            /*####################### VALIDATION #########################*/ 

            if ((username_input.Text == "") && (Password_input.Text == ""))
            {
                ErrorLogin_Lbl.Text = "Please enter your initials and password";
            }

            else if (username_input.Text == "")
            {
                ErrorLogin_Lbl.Text = "Please enter your initials";
            }
            else if (Password_input.Text == "")
            {
                ErrorLogin_Lbl.Text = "Please enter your password";
            }

            else 
            {
                ErrorLogin_Lbl.Text = "";

                /*################## CHECKING IF IN DATABASE ##################*/
                string sConnection = "Provider=SQLOLEDB;Data Source=RITZEL-PC@SQLEXPRESS;Integrated Security=SSPI;Initial Catalog=NNIT-RMS";
                OleDbConnection dbConn = new OleDbConnection(sConnection); //database connection
                dbConn.Open(); //open connection

                //retrieve data from database
                string UsersDB = "SELECT UserID, Initials, Password FROM dbo.Users";

                OleDbCommand dbCommand = new OleDbCommand;
                dbCommand.CommandText = UsersDB;
                dbCommand.Connection = dbConn;

               OleDbDataReader dbReader = dbCommand.ExecuteReader();
                      
             }

        }


    }
}

[noshaba]

please guide me step by step how can i develop a website with email service. i also have to use attachments with email message