For this step you will need your wide ribbon, thin ribbon*, tape, tape cutting scissors (or other tape cutting device), ribbon cutting scissors and hot glue gun.
*optional
Take your wide ribbon and cut one 1" pieces/squares (I will refer to them as squares) for cupcakes, two for custom theme cakes, three for elegant cakes or four for mega/deluxe cakes as shown:
Take one square (the others will go on the two other tiers) and tuck it behind or near the spot where the curling ribbon is tied (aka the back of the cake) as shown:
This square will give your wide ribbon something to hold on to without getting glue on the diapers. If the piece is too loose or falls out, then your curling ribbon is not tight enough.
Hot glue your wide ribbon to the square,
wrap around the tier,
then cut the end (make sure it is a nice, straight cut and meets up with the other end nicely) and hot glue the end.
Your ribbon should be right in the middle of the diapers all the way around. It should also fit snug, not too tight or too loose as shown:
As this point you can add your thin ribbon around the center of the wide ribbon using the same technique OR wait until all the tiers are done OR not add thin ribbon at all.