C#如何实现用户名与密码登录

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;
namespace _1_3
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            textBox2.PasswordChar = '*';//密码以星号显示
        }
        private void textBox1_TextChanged(object sender, EventArgs e)
        {
        }
      private void textBox2_TextChanged(object sender, EventArgs e)
        {
      }
        private void button2_Click(object sender, EventArgs e)
        {
            textBox1.Text = "";//清空文本框内容，下同
            textBox2.Text = "";
        }
        private void button1_Click(object sender, EventArgs e)
        {
            String st1 = textBox1.Text.Trim();//获取文本框内容
            String st2 = textBox2.Text.Trim();
            if(st1=="1808080112"&&st2=="123456")
            {
                MessageBox.Show("登陆成功！");
            }
            if (st1!="1808080112"&&st2=="123456")
            {
                MessageBox.Show("用户名错误！");
                textBox1.Text = "";
            }
            if(st1=="1808080112"&&st2!="123456")
            {
                MessageBox.Show("密码错误！");
                textBox2.Text = "";
            }
            if(st1!="1808080112"&&st2!="123456")
            {
                MessageBox.Show("用户名、密码错误！");
                textBox1.Text = "";
                textBox2.Text = "";
            }
        }
    }
}