What it means is that you bind off 9 stitches, then drop your yarn. Put 24 stitches on a holder, then JOIN A SECOND BALL OF YARN and bind off hte last 9 stitches.
However, you're finishing will be a lot easier if for the back you put 9 stitches on one holder, 24 on another, and final 9 on another holder.
Then go to the front. I'm not clear from what you have written what is going on, but bascially at some point you will end up 9 stitches bound off on each end. Again, if you put these on a holder, you can then join them the 9 stitches from the back using 3-needle bind-off. I'm sure Amy has a tutorial on this.
Hope this helps