Datagridview Insert Row

i have a datagridview with 2 columns on it.

i add column 1 manually from Datagridview task (add columns), it should numeric value and came from user input.

for column 2 (it's numeric value), on load event from database with this :

Using conn As New MySqlConnection("connection string")
                conn.Open()
                Dim command As New MySqlCommand("select amount from my_tabel_in_database", conn)
                Dim adapter As New MySqlDataAdapter
                Dim dt As New DataTable
                adapter.SelectCommand = command
                adapter.Fill(dt)
                DataGridView1.DataSource = dt
                adapter.Dispose()
                command.Dispose()
                conn.Close()


   Dim total1, total2 As Double
            For i As Integer = 0 To DataGridView1.Rows.Count - 1
                total1 += DataGridView1.Rows(i).Cells(0).Value
                total2 += DataGridView1.Rows(i).Cells(1).Value
            Next
            Dim myrow = dt.NewRow
            myrow(0) = total1
            myrow(1) = total2
            dt.Rows.Add()
            dt.Rows.Add(myrow)
End Using

my purpose is to add total1 and total2 in bottom of that both column, but i get this error :

Cannot find Column 1

i know the reason, it's because total1 is un-bound and total2 is bound.

my question is, how to insert that both total in the bottom of column?

thanks.