How to find CheckBox control in DataGridView?

How to add item of checkbox in datagridview(2) to datagridview(1) for show data in checkbox(database) on datagridview(1)

My code

DataTable a = tablebill();
foreach (DataGridViewRow row in dataGridView1.Rows)
{
    bool checkBoxValue = Convert.ToBoolean(row.Cells[0].Value);
    if (checkBoxValue == true)
    {
        a.Rows.Add(row.Cells["Products"].Value);
    }
    else { }
}
dataGridView1.DataSource = a;