Although I prefer twisting each loop, some florists simply "pinch" the center of the ribbon together, creating a pleat right in the middle where the wire will go later.
Either is fine, just be sure both the ribbon and tulle are pleated or twisted at the same time.
Fold over the ribbon to form a loop about the width of your hand. Slide the ribbon between your middle and third finger. With those fingers holding the ribbon, twist it firmly and add THAT twist to the original one you hold between your index and thumb.
A closer view shows that the two twists are now held firmly between the index finger and the thumb.
You will now fold the lower, dangling portion (still attached to the ribbon spool) into another matching loop.
This is how it looks with the first loop.
My third finger on my right hand now pinches the outer tulle and ribbon that is dangling down.
With another twist, I have added a matching loop to the second side. The tails are shown on the right side of the picture, the ribbon and tulle trailing off to the left is still attached to the bolt of ribbon.