Log In Form in window apps

1) Create your log in form as a separate class, derived from Form: call it frmLogin or similar.
2) Create an instance in your main Form Load event.
3) Show the login form as a modal dialog.
4) Check the users responses to ensure his user details are ok.

bool loggedIn = false;
while (!loggedIn)
   {
   frmLogin f = new frmLogin();
   if (frmLogin.ShowDialog == DialogResult.Cancel)
      {
      Close();
      return;
      }
   if (IsGoodLogin(f.UserName, f.Password))
      {
      loggedIn = true;
      }
   }

Then all you have to do is write IsGoodLogin - I can't help as I don't know anything about how you store names and passwords. However there is a note on password storage here: Password Storage: How to do it.[^]

A simple Windows Forms Login Control component[^]

Create 2 lable controland text box Uname and password and 2 command button names are (1) btnlogin and (2) btnCancel

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.Security.Cryptography;


namespace Test
{
    public partial class Log_In : Form
    {
        public Log_In()
        {
            InitializeComponent();
        }

              private void btnlogin_Click(object sender, EventArgs e)
        {
          if (txtUname.Text == ("Admin"))
            {
                if (TxtPassword.Text == ("QRSV"))
                {
                    Addapt a = new Addapt();
                    a.Show();
                }
          }
        }

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

        }
    }
}