private void btnSil_Click(object sender, EventArgs e)
{
MusteriBL musteribl = new MusteriBL();
Id = Convert.ToInt32(grdMusteri.SelectedRows[0].Cells[1].Value);// burda ıd göndermemizin sebebi sil metodunda parametre olarak ıd istenmesi
musteribl.Sil(Id);
}