need code for login in asp.net with c#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;
using System.Web.Configuration;
public partial class Login : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Login1_Authenticate(object sender, AuthenticateEventArgs e)
{
string username = Login1.UserName;
string pwd = Login1.Password;
string s;
s = WebConfigurationManager.ConnectionStrings["ChartDatabaseConnectionString"].ConnectionString;
SqlConnection con = new SqlConnection(s);
con.Open();
string sqlUserName;
sqlUserName = "SELECT user_name,password FROM Login WHERE user_name ='" + username + "' AND password ='" + pwd + "'";
SqlCommand cmd = new SqlCommand(sqlUserName, con);
string CurrentName;
CurrentName = (string)cmd.ExecuteScalar();
if (CurrentName != null)
{
Session["UserAuthentication"] = username;
Session.Timeout = 1;
Response.Redirect("start.aspx");
}
else
{
Session["UserAuthentication"] = "";
}
}
}