Creating "Registration Form"using Windows Application

Example:  Creating registration Form in Windows Application using CSharp

Design as following, define a validating event procedure for user name textbox and bind that event procedure with both password textbox's. Now write  the following code under the Validating Event Procedure:

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 WinForms7
{
    public partial class Form4 : Form
    {
        public Form4()
        {
            InitializeComponent();
        }

        private void txtname_Validating(object sender, CancelEventArgs e)
        {
            TextBox tb = sender as TextBox;
            if (tb.Text.Trim().Length == 0)
            {
                MessageBox.Show("Cannot leave empty");
                e.Cancel = true;
                return;
            }
            if (tb.Name =="txtpass")
            {
                if (tb.Text.Trim().Length < 8)
                {
                    MessageBox.Show("Pwd should be between 8 to 16 chars");
                    e.Cancel = true;
                    return;
                }
                if(tb.Name=="txtCPass")
                {
                    if(txtPass.Text .Trim()!=txtPass.Text.Trim())
                    {
                        MessageBox.Show("Conform pwd should match with pwd");
                        return;
                    }
                    btnSave.Enabled=true;
                }
            }

            }

        private void btnClose_Click(object sender, EventArgs e)
        {
            txtname.CausesValidation = false;
            txtPass.CausesValidation = false;
            txtCPass.CausesValidation = false;
            this.Close();
        }

        private void txtPhone_KeyPress(object sender, KeyPressEventArgs e)
        {
            //MessageBox.Show(Convert.ToInt32(e.KeyChar.ToString()));
            if (char.IsDigit(e.KeyChar) == false && Convert.ToInt32(e.KeyChar) != 8)
                MessageBox.Show("Enter numeric only");
            e.Handled = true;
   
        }

        private void btnSave_Click(object sender, EventArgs e)
        {
         //need to write code for saving data to database here
            MessageBox.Show("Data saved to database");
        }

        private void btnClear_Click(object sender, EventArgs e)
        {
            foreach (Control ctrl in this.Controls)
            {
                if (ctrl.GetType().Name == "TextBox")
                {
                    TextBox tb = ctrl as TextBox;
                    tb.Clear();
                }
                btnSave.Enabled = false;
                txtname.Focus();
            }
        }
                 
      }
    }