Log-In Page

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Data.SqlClient;

namespace Gwenchaners_Voting_System_Project
{
    public partial class LogInPage : Form
    {
        SqlConnection con = new SqlConnection();
        SqlCommand com = new SqlCommand();


        public LogInPage()
        {

            InitializeComponent();
            con.ConnectionString = @"Data Source=DESKTOP-NDPHD3N;Initial Catalog=UserVoters;Integrated Security=True";
        }

        private void btnLogin_Click(object sender, EventArgs e)
        {
            con.Open();
            com.Connection = con;
            com.CommandText = "select * from UserInfo";


            if (dr.Read())
            {
                if (txtboxIDNo.Text.Equals(dr["ID Number"].ToString()) && txtboxPassword.Text.Equals(dr["Password"].ToString()))
                {
                    this.Hide();
                    Homepage homepage = new Homepage();
                    homepage.Show();
                }

                else
                {
                    MessageBox.Show("Either your ID Number or your Password is Incorrect. Please Try Again.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }


            }
            con.Close();
        }

        private void txtboxIDNo_TextChanged(object sender, EventArgs e)
        {
            if (txtboxIDNo.Text.Equals("IDNo"))
            {
                txtboxIDNo.Text = "";
            }
        }

        private void txtboxPassword_TextChanged(object sender, EventArgs e)
        {
            if (txtboxPassword.Text.Equals("Password"))
            {
                txtboxPassword.Text = "";
            }
        }

        private void checkBoxShowPassword_CheckedChanged(object sender, EventArgs e)
        {
            if (checkBoxShowPassword.Checked == true)
            {
                txtboxPassword.UseSystemPasswordChar = false;
            }
            else
            {
                txtboxPassword.UseSystemPasswordChar = true;
            }
        }
    }
}