how to authenticate web form in asp.net using C#

Question

 

protected void 
btnlogin_Click(object sender, EventArgs e)

{

if (txtid.Text == "" || txtpswd.Text 
== "")

{

Response.Write("<script>alert('Enter Id & 
Password')</script>");

}

else

{

string strname = txtid.Text;

string strpswd = txtpswd.Text;

OdbcConnection con = new 
OdbcConnection("DRIVER={MySQL ODBC 3.51 
Driver};SERVER=localhost;DATABASE=hdesk;uid=root;password=pssone;");

con.Open();

OdbcCommand cmd = new OdbcCommand("select 
count(e_uid) from emp_mast where e_uid = '" + strname 
+ "' and e_pswd = 
'" + strpswd + "' and e_accept = 'Y'", con);

OdbcCommand cmd1 = new OdbcCommand("select 
e_uid from emp_mast where e_uid = '" + strname + 
"'", con);

if (Convert.ToInt32(cmd.ExecuteScalar().ToString()) > 0)

{

string uid = 
cmd1.ExecuteScalar().ToString();

if (uid == "admin")

{

Session.Add("muser", txtid.Text);

Response.Redirect("AdminApproval.aspx");

}

else

{

Session.Add("muser", txtid.Text);

Response.Redirect("UserHome.aspx");

clearlist();

}

}

else

{

Response.Write("<script>alert('Invalid user Id & 
Password')</script>");

clearlist();

}

}

}

i written above code for login to userhome.aspx page.
when it is redirected  userhome.aspx page i written below code for logout

 

protected void 
btnsout_Click(object sender, EventArgs e)

{

Session.Clear();

Response.Redirect("Default.aspx");

}

when i click signout from userhome.aspx it will redirected to loginpage. if i copy the the address box string like
http://localhost:1446/t%20work/hdesk/UserHome.aspx
it will again redirects to userhome.aspx without propting username and password even thouigh i cleared sesssion.
please help me to overcome from this problem.