ASP.Net

How to get data from database in asp.net

{
        SqlConnection conn = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=C:\Users\123\Documents\Visual Studio 2008\WebSites\Elysian\App_Data\Elysian.mdf;Integrated Security=True;User Instance=True");
        SqlCommand cmd;
        try
        {
            cmd = new SqlCommand("Select * from Signup Where Email_address ='" + txtstff.Text + "'And Password='" + txtPsd1.Text + "'", conn);
            conn.Open();
            cmd.ExecuteNonQuery

 {
        SqlConnection conn = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=C:\Users\123\Documents\Visual Studio 2008\WebSites\Elysian\App_Data\Elysian.mdf;Integrated Security=True;User Instance=True");
        SqlCommand cmd;
        try
        {
            cmd = new SqlCommand("Select * from Signup Where Email_address ='" + txtstff.Text + "'And Password='" + txtPsd1.Text + "'", conn);
            conn.Open();
            cmd.ExecuteNonQuery();
            SqlDataReader reader = cmd.ExecuteReader();
            if (reader.Read())
            {
                //cmd = new SqlCommand("select First_Name+' '+Last_Name as 'user name' from Signup where email_address ='" + txtstff.Text + "'", conn);
                //conn.open();
                //cmd.ExecuteNonQuery();
               // SqlDataReader reader = cmd.ExecuteReader();
                reader.Close();
                conn.Close();
                Session["user name"] = txtstff.Text;
                Session.Timeout = 240;
                Response.Redirect("staff.aspx");
            }
            else
            {
                lblstff.Text = "Incorrect Email address or Password";
                //lblerroradmin.Text = "Incorrect password, This site is only for admin";
            }
        }
        catch
        {
            conn.Close();
        }
     
    }

How to insert data in database by using asp.net

 {
        SqlCommand cmd;
        SqlDataReader reader;
        SqlConnection conn = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=C:\Users\123\Documents\Visual Studio 2008\WebSites\Elysian\App_Data\Elysian.mdf;Integrated Security=True;User Instance=True");
        cmd = new SqlCommand("Select * from Student Where Email_Address='" + txteadrs.Text + "'", conn);
        conn.Open();
        reader = cmd.ExecuteReader();
        if (reader.Read())
        {
            reader.Close();
            conn.Close();
            txteadrs.Text = "";
            txtnme.Text = "";
            txtfnme.Text = "";
          
           // lblreg.Text = " Dear Staff You have been already registered....! thanks for joining";
            lblstndreg.Text = "Dear Student you have already registered.....! thanks for joining";
        }
        else
        {
            //conn.Open();
            reader.Close();

            cmd = new SqlCommand("Insert into Student(First_Name,Last_Name,Fathers_Name,Email_Address,DOB,Class_Id,Section,Field_of_Study,Gender,Address,Contact_No) Values('" + txtnme.Text + "','" + txtnme.Text + "','" + txtfnme.Text + "','" + txteadrs.Text + "','" + txtdob.Text + "','" + DropDownList1.SelectedValue.ToString() + "','" + txtsec.Text + "','" + ddlfostdy.Text + "','" + ddlgndr.Text + "','" + txtadd.Text + "','" + txtcno.Text + "')", conn);       
            cmd.ExecuteNonQuery();
            conn.Close();
            //lblsgnup.Text = "Your account has been successfully created";
            lblstndreg.Text = "Student Added Successfully";
            //Response.Redirect("regsternotification.aspx");
        }
    }