how to add checked rows of datagridview into database

Question

how to add checked rows of datagridview into database in visual studio 2010 windows application form.
plz help

i hd written this code but throwing error on CheckBox chkbx = (CheckBox)row.FindControl("chkbx"); this line.

foreach (DataGridViewRow row in dataGridView1.Rows)

            {

                CheckBox chkbx = (CheckBox)row.FindControl("chkbx");

                if (chkbx .Checked == true )

                {

                    con.Close();

                    con.Open();

                    com.Connection = con;

                    string str = "insert into EmpDetails values ('" + row.Cells[2].Value.ToString() + "','" + row.Cells[3].Value.ToString() + "')";

                    com.CommandText = str;

                    dr = com.ExecuteReader();

                    MessageBox.Show("Success.....");

                    dr.Close();

                }