The bindings need to be cut to the thickness of the book (when all signatures are together) plus an inch or so.
The first signature you should sew are the first endpages, followed by signature 1 of the book, then the rest.
Insert the needle *into* the head and draw all but about 2 inches through. Then go *out* at the first punch you come to and pull it tight. Go *in* to the next hole-- but make sure that the binding is between the thread and the spine (as in the image). Repeat for as many bindings as there are, then come out through the foot notch. Prepare the next signature.