Help with datagridview

Question

Hi there,
Ok I have this problem:
I have a databound datagridview from a child table with four collums in it:
 
 SongName  
 SongUrl

 CdNumber   that is F_key
 SongNumber that is primary key identity yes

none of them accept null value

CdNumber is the F_key from the parent CdNumber that is primary key

so my question is when I add row how do I enter the info for CdNumber and SongNumber
because getting error that CdNumber and SongNumber can't be null

1	using System;
2	using System.Windows.Forms;
3	using System.IO;
4
5	namespace MusicOrganiser
6	{
7	public partial class NewEntry : Form
8	{
9
10
11	Form1 mainForm;
12	public NewEntry(Form1 mainForm)
13	{
14	this.mainForm = mainForm;
15
16	InitializeComponent();
17	}
18
19	private void button1_Click(object sender, EventArgs e)
20	{
21	this.folderBrowserDialog1.ShowNewFolderButton = false;
22	DialogResult result = this.folderBrowserDialog1.ShowDialog();
23	if (result == DialogResult.OK)
24	{
25	// retrieve the name of the selected folder
26	DirectoryInfo dir = new DirectoryInfo(this.folderBrowserDialog1.SelectedPath);
27
28	// Entries for the first table
29	mainForm.categoryTextBox.Text = comboBox1.Text;
30	mainForm.artistTextBox.Text = textBox1.Text;
31	mainForm.albumTextBox.Text = dir.Name;
32
33	DataMusicDataSet.SongFilesRow newrow = dataMusicDataSet1.SongFiles.NewSongFilesRow();
34
35	//Now to get every song in the folder or cd
36	foreach (FileInfo fi in dir.GetFiles())
37	{
38
39	newrow.Song = fi.ToString(); // Getting filename
40	newrow.SongUrl = fi.FullName; // Getting full path to play the song when click
41
42	dataMusicDataSet1.SongFiles.Rows.Add(newrow);
43	//mainForm.songbindingNavigator.BindingSource.Add(newrow);
44
45	}
46	}
47	else
48	{
49	//If cancel close form NewEntry
50	this.Close();
51	}
52
53
54	}
55
56	private void OK_Click(object sender, EventArgs e)
57	{
58	this.Close();
59	}
60
61
62	}
63	}
64

 

When running the program and enter everything to the datagrid manualy everything works 100% but I want to be able to enter automaticly from the second form. I don't have any problem for the first table it is when it come to the second one for the song table