SqlConnection cnn = new SqlConnection(ConfigurationManager.ConnectionStrings[0].ConnectionString);
string sorgu = "Insert into Kullanicilar (KullaniciAdi, Sifre) Values (@kullaniciadi,@sifre)";
SqlCommand cmd = new SqlCommand(sorgu, cnn);
cnn.Open();
cmd.Parameters.AddWithValue("@kullaniciadi",txtKullaniciAdi.Text);
cmd.Parameters.AddWithValue("@sifre", txtSifre.Text);
cmd.ExecuteNonQuery();
cnn.Close();