private void formAçToolStripMenuItem_Click(object sender, EventArgs e)
        {

         Form2 frm2 = new Form2();

     frm2.ShowDialog();
        }

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;

namespace contextMenu
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void formAçToolStripMenuItem_Click(object sender, EventArgs e)
        {
          
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        private void button1_Click(object sender, EventArgs e)
        {

if (textBox1.Text.ToLower().Trim()=="admin" && textBox2.Text.Trim().ToLower()=="1")
            {

                this.Hide();

Form2 frm2 = new Form2();

frm2.label1.Text = "Hoşgeldin " + this.textBox1.Text;

frm2.Show();
            }
            else
            {

MessageBox.Show("Kullanıcı adı veya şifreniz hatalı", "Hatalı Giriş", MessageBoxButtons.OK, MessageBoxIcon.Error);

textBox1.Focus();
            }
        }
    }
}

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;

namespace contextMenu
{
    public partial class Form2 : Form
    {
        public Form2()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {

Application.Exit();
        }

        private void Form2_FormClosing(object sender, FormClosingEventArgs e)
        {

 Application.Exit();
        }

        private void label2_Click(object sender, EventArgs e)
        {

        }

        private void button2_Click(object sender, EventArgs e)
        {
            
            MessageBox.Show("Kişi adres defterine kaydedildi");

     for (int i = 0; i < this.Controls.Count; i++)
            {

  if (this.Controls[i] is TextBox)
                {

  this.Controls[i].Text = "";

                } 
            }
            

        }
    }
}