Slide a film leading tip into a gap of spool	Wind up	Done

First, load a 120 roll film into a camera which uses a 120 roll film, and then wind it up till the end.
*In case you use a camera to wind up a film, use the one with no device that locks the film winding one at a time.

cameras which use 620 roll film

ANSCOFLEX2

KODAK MEDALIST