Dennis,
Do you see the one in the photo on the left side on the spool? If you take the spool in that orientation you can see in the photo and hold the left side in the left hand and the right side in the right hand, then turn the right side towards you (twist the Rt hand thumb towards your body). There's a slight catch and then the two sides will rotate so that the "key" that you can see in the track is now no longer visible in the slot and you'll be able to pull the two sides apart and then reverse the twist in a slot that spaces the sides properly for 120 film.
A person wanting to process 120 film will probably want to get the little red roll spacer tabs from B&H to divide two rolls on a spool, but otherwise, this set will get a lot of processing done.