Use the thermal adhesive to attach the resistors to the notches in the aluminum block. The adhesive takes about 5 min to set, make sure the surfaces are flush (this will determine how fast you can transfer heat to the sample).
You can also use the thermal adhesive to glue the end of the thermocouple wire to the block (that's where the temperature is sensed). You'll get better accuracy if you embed the wire in the block. You can drill a small hole at the top, between the PCR tube holes and attach the thermocouple to that.