Login with ASP.NET and database

I have to login with ASP.NET using database by different way. This is my code

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;
using System.Data;

namespace OkulYonetimSistemi.DATA
{
    public class Giris
    {
        public string _connectionString;
        public string SQL_Oku = "usp_login";


        public Giris(string connectionString)
        {
            _connectionString = connectionString;
        }

        public DataSet DsGonder(string Telno , string Sifre)
        {
            using (SqlConnection con = new SqlConnection(_connectionString))
            {
                con.Open();
                SqlCommand cmd = new SqlCommand(); cmd.Connection = con;
                cmd.CommandText = SQL_Oku;
                cmd.CommandType = System.Data.CommandType.StoredProcedure;
                cmd.Parameters.AddWithValue("@Telno",Telno);
                cmd.Parameters.AddWithValue("@Sifre", Sifre);

                SqlDataAdapter da = new SqlDataAdapter(cmd);
                DataSet ds = new DataSet();
                da.Fill(ds);
                return ds;
            }
        }
    }
}

This is a class that I should use in my login.cs and I don't know how should I use that class in main code.

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace KuaforSitesi
{
    public partial class giris : System.Web.UI.Page
    {

        string SQL_string = ConfigurationManager.ConnectionStrings["EgitimBilgiConnectionString"].ConnectionString;

        protected void Button_Click(object sender, EventArgs e)
        {
            OkulYonetimSistemi.DATA.Giris Giris = new OkulYonetimSistemi.DATA.Giris(SQL_string);
            Giris.DsGonder(txttelno.Text, txtsifre.Text);
        }
    }
}

txttelno is user and txtsifre is password

and procedure is very simple that take 2 values like this

select ad, soyad
from Musteri
where Telno = @Telno and Sifre = @Sifre

Can someone help me to login with this way please?