protected void button_Click(object sender, EventArgs e)
    {

        DBKariyerBL.User user = new DBKariyerBL.User();
        user.UserName = txtKlnAd.Text;
        user.Password = txtParola.Text;
        if (user.Login(user))
        {
            Session["LogIn"] = "1";
            Response.Redirect("Default.aspx");
        }
    }

public class User
    {
        public string UserName { get; set; }
        public string Password { get; set; }

        SqlConnection conn = new SqlConnection(Util.ConnectionString);

        public bool Login(User user)
        {
            return Convert.ToInt32(SqlHelper.ExecuteScalar(conn, CommandType.Text, "SELECT COUNT(*) FROM Users WHERE UserName=@UserName AND Password=@Password", new SqlParameter[] { new SqlParameter("@UserName", user.UserName), new SqlParameter("@Password", user.Password) })) > 0;
        }


    }

public class User : System.Web.Services.WebService
{

    [WebMethod]
    public bool Login(DBKariyerBL.User user)
    {
        DBKariyerBL.User kull = new DBKariyerBL.User();
        return kull.Login(user);
    }
}

public class Util
{

    public static string ConnectionString
    {
        get { return ConfigurationManager.ConnectionStrings["SqlConnection"].ConnectionString; }
    }
}

public class Util
  {

public static string ConnectionString
{
    get { return  "Data Source=ServerName;" +
"Initial Catalog=DataBaseName;" +
"User id=UserName;" +
"Password=pwd;"; }
}
}