throw and catch exception handling

Hi,
iam inserting record in three tables in a database, iam using begin trans , commit transaction and rollback,
i want to use throw method, if  any value insert wrong, pls correct me, i want to throw the error and
its go to rollback

running = false;
                        int updaterec = DBmgr.ExecuteNonQuery(CommandType.Text, "update ASArrivedcontainer set billgen ='Y' where billgen ='y' and acontinerid in ("+SelValues+")");
                        if (updaterec > 0)
                        {
         & ...