BookMark Finishing
To determine the size fabric you need to make your book mark...... grab a piece of paper and a pencil.

Discover the height and width stitch count of the design you plan to stitch. 

In this example it is  21 stitches wide X  81 stitches high.

Add 6 to the width of  the design: 21 + 6 = 27  (for white space around the design)
Double that total: 27 x 2 = 54
Add 10 for seam allowances:  54 + 10 = 64

Add 16 to the height of the design:  81 + 16 = 97

For this design, your fabric needs to be   64  squares wide by  97 squares high.
fig. 1  
Centre design exactly on fabric. 
                                                               fig. 2  
Line up long sides with front of design facing in.  With 2 strands of floss, sew a simple running stitch, matching hole for hole starting 5 sqares in from the long edge and 5 squares from the top, stopping 5 squares from the bottom.   (fig. 3)  
Anchor thread in the seam allowance. 
fig. 3
                                                               fig. 4
Finger press seam allowance to lay flat.
fig. 5 
Turn one end of bookmark to right side out, keeping seam allowance inside flat. 
                                                   fig. 6
Continue to turn bookmark right side out
Wearing a latex glove made the turning easier.
Pull the threads out of the top and bottom 5 rows of squares to make fringed edges.

Sprinkle with water and press with a pressing cloth, making sure you have folded it so as to have 3 squares of white space on each side of the design. 
Back view
*dark thread was used for demo purposes