login page asp.net sql - asp.net

Question

I have this code and need to complete it..
string conn_str =
#"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\mydb.mdf;
Integrated Security=True;User Instance=True";
SqlConnection conn = new SqlConnection(conn_str);
SqlCommand cmd = new SqlCommand("SELECT Password FROM Users WHERE UserName=#un", conn);
cmd.Parameters.Add("#un", SqlDbType.NVarChar);
cmd.Parameters["#un"].Value = **???**;
conn.Open();
string pwd = (string)cmd.ExecuteScalar();
conn.Close();
I have some values in sql data:
Tables:
Users
Username
Password
Now in login page i have textboxNAME and textboxPassword and if user type right login info(that in database) it refers him to default.aspx

Answer 1

Try
cmd.Parameters["#un"].Value = textboxName.Text;
and
if(textboxPassword.Text.Equals(pwd))
{
Request.Redirect("default.aspx");
}
else
{
//login failed
}

Answer 2

Try This:
string conn_str = #"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\mydb.mdf; Integrated Security=True;User Instance=True";
private string _password;
SqlConnection conn = new SqlConnection(conn_str);
SqlCommand cmd = new SqlCommand("SELECT Password FROM Users WHERE UserName=#un", conn);
cmd.Parameters.Add("#un", SqlDbType.NVarChar,50).Value=txtusername.text;
//use add with value to specify which object you want to use
SqlDataAdapter adapt = new SqlDataAdapter(cmd);
//load data to datatable
DataTable dt = new Datatable();
conn.Open();
adapt.Fill(dt);
//get Password on Datatable
Foreach(DataRow a in dt.Rows)
{
_password = a["Password"].Tostring();
}
//Check password
if(_password==string.Empty)
{
//remain
}
else if(_password==txtpassword.Text)
{
Response.Redirect("My page");
}
conn.Close();
Regards