Step 1: Gather Your Materials
Sorry it's sideways...
Step 2: Cut Your String
Make sure the string you cut is a little longer than your book. ( I am using "The Vile Village" from the 'A Series of Unfortunate Events' by Lemony Snicket )
Step 3: Cut More Strings
I used 5 strings, blue, yellow, red, purple, and green. Make sure they are all the same length.
Step 4: Braid!
Braid your strings, alternatively you could twirl them, as shown
Step 5: Keep Braiding
Keep braiding until your braid is as long as your book, and it can be longer
Step 6: Tie and Glue
Tie off the braid, but make sure the knot is placed below the book so it can close flat, then glue the short end of tassels between the inside of the cover and the first page.
Step 7: Finish!
Allow the glue to dry before closing the book, since it might cause problems when opening the book. Hope you enjoyed, this was my first instructable ;)