how to insert multiple values in a table? using c#

connectionString = @"Data Source=HP\SQLEXPRESS;database=MK;Integrated Security=true";
 connection = new SqlConnection(connectionString);
 foreach (int rowIndex in lstNewRows)
 {
 string insrtQry = "insert into " + comboBox1.Text + " values(";

 foreach (DataGridViewCell cell in dataGridView1.Rows[rowIndex].Cells)
 {
 insrtQry += "'" + cell.Value.ToString() + "',";
 }

 insrtQry = insrtQry.TrimEnd(",".ToCharArray());

 insrtQry += ")";

 try
 {
 connection.Open();
 adapter.InsertCommand = new SqlCommand(insrtQry, connection);
 adapter.InsertCommand.ExecuteNonQuery();

 MessageBox.Show("Row inserted !! ");
 }
 catch (Exception ex)
 {
 MessageBox.Show(ex.ToString());
 }
 }
 }

 private void insert_Click(object sender, EventArgs e)
 {
 InsertInfo();
 }

 private void dataGridView1_DefaultValuesNeeded(object sender, DataGridViewRowEventArgs e)
 {
 lstNewRows.Add(e.Row.Index);
 }