Find a point about 2" to one side of the center back of the needlebook, and another point 2" to the other side of the center back of the needlebook. Use colored pins to mark these two points. If you don't have colored pins, just use two pins in the same place as your marker. (Note the pink and black marker pins in the sample.)

Following the stitching that you made to attach the piping, make a line of basting 1/8" away from that stitching in the seam allowance. Remove all pins except the ones that mark the 2" points on either side of the center.

While it may seem annoying to be doing all this basting, it really does help to keep everything smooth. Pins are great, but they create bulk. With this many layers, it is best to machine sew with hand basting keeping things together than with pins.

Note: Make sure that your tassel is situated out of the way of the seam allowances. You may choose to wrap it in a piece of muslin and pin it down while you are stitching the edges of the needlebook.