You can simply call the Toronto office or email them with your booking reference number.
However, you may wish to call Aeroplan to get the Turkish Airlines reference number. As the reference number given to you by Aeroplan applies only to Air Canada flights, and Turkish would have generated a reference number of their own for the TK flights you are booked on.
The staff at the Toronto office are super friendly and helpful. If you want to see a seat map, then it's best to go in person to book the seats in person. Otherwise, you can call or email if you simply have a preference for aisle or window seats.
They do have standard office hours, so your lunch hour is probably your best bet.