Getting ID of record just inserted?

I am processing items users have selected from a gridview, and performing an email and database insert operation.

When the user selects a button, the code below takes information from the gridview, creates a new order in the Order table, and creates new entries in the Transactions table.

How can I get the last inserted ID if I use this method of inserting a record? Would you recommend a different approach to this simple problem?

protected void btnOrder_Click(object sender, EventArgs e)
{
    double Total = 0;
    string MailFrom = "webadmin@domain.com";
    string MailTo = "purchasing@domain.com";
    string MailSubject = "Online Order";
    string MailCC = "";
    string MailBCC = "";
    string MailReplyTo = "";
    string MailBody = "";

    TextBox ItmCostCode = (TextBox)form1.FindControl("txtCostCode");

    foreach (GridViewRow gvr in GridView1.Rows)
    {
        CheckBox cb = (CheckBox)gvr.FindControl("ItemSelect");
        Label ItmTotal = (Label)gvr.FindControl("ItmTotal");
        Label ItmPrice = (Label)gvr.FindControl("ItmPrice");
        Label ItmName = (Label)gvr.FindControl("lblName");
        TextBox ItmQty = (TextBox)gvr.FindControl("ItmQty");
        TextBox ItmID = (TextBox)gvr.FindControl("lblItemID");

        //Add entry to Order Table
        SqlDataSource2.InsertParameters.Add("OrderDate", DateTime.Now.ToString("MMMM dd, yyyy"));
        SqlDataSource2.InsertParameters.Add("OrderTotal", "0");
        SqlDataSource2.InsertParameters.Add("OrderAccount", "name");
        SqlDataSource2.InsertParameters.Add("OrderCostCentre", ItmCostCode.Text);
        SqlDataSource2.Insert();

        //TODO: GET ORDERID HERE TO USE BELOW:
        if (cb.Checked)
        {
            double Price = Convert.ToDouble(ItmPrice.Text);
            double Qty = Convert.ToDouble(ItmQty.Text);

            Total = Price * Qty;
            OrderTotal = OrderTotal + Total;

            MailBody = MailBody + "Item: "+ItmName.Text+" Quantity: "+ItmQty.Text+" Total: "+ItmTotal.Text+"\n\r";

            //Add entry to Transaction Table
            SqlDataSource3.InsertParameters.Add("ItemID", ItmID.Text);
            SqlDataSource3.InsertParameters.Add("OrderID", );
            SqlDataSource3.InsertParameters.Add("Price", ItmPrice.Text);

            SqlDataSource3.Insert();
        }

        //TODO: Update Order table with OrderTotal
    }

    string strOrderTotal = OrderTotal.ToString();

    MailBody = MailBody+"Order Total: " + strOrderTotal+"\n\r";
    MailBody = MailBody + "Cost Code: " + ItmCostCode.Text;

    MailService.Service1 Mailer = new MailService.Service1();
    Mailer.SendMail("Text", MailFrom, MailTo, MailCC, MailBCC, MailSubject, MailBody, MailReplyTo);
}