' Change the text in the column header.
Private Sub Button9_Click(ByVal sender As Object, _
    ByVal args As EventArgs) Handles Button9.Click

    For Each column As DataGridViewColumn _
        In dataGridView.Columns

        column.HeaderText = String.Concat("Column ", _
            column.Index.ToString)
    Next
End Sub

// Change the text in the column header.
private void Button9_Click(object sender,
    EventArgs args)
{
    foreach (DataGridViewColumn column in dataGridView.Columns)
    {

        column.HeaderText = String.Concat("Column ",
            column.Index.ToString());
    }
}