Hi Pauline
I basically just glued the signatures to a fiberglass mesh as shown in post #264 of this thread. Use a glue that is flexible when it dries and you should have no problem. You could use hot glue from a glue gun but you have to work quickly cause it dries pretty fast. I used a white glue that is meant for book binding. Don't remember where I got it or what it is called but it is pretty easy to find. You can also take some heavy thread and weave it between the binding string of each signature and the fiberglass mesh for extra holding power if you like. I recommend you experiment first before you jump in on the actual book you are making.
I actually used a fiberboard from clipboards I bought at the local dollar store. I thought they gave a nice solid feeling to the book and they won't bend under use or when the book slouches down on the bookshelf. You could just as easily use heavy cardboard as well. My idea to complete the book was to join the 2 covers with a piece of brown leather (glued to each cover) which would have a heavy cardboard spine piece. Have not done that yet.
Good luck, post a few pics as you go and when you are done.
bfd