Make a list of the parts of the book you wish to storyboard. You might storyboard the book by paragraphs or by chapters. Create an outline of the scenes so that you know how many index cards to prepare.
Draw a representation of the scene on the index card. Use one index card per scene. The index card should include an image of the character or characters, a representation of the background where the action is taking place and a depiction of the actions of the characters themselves. Make the visual elements as faithful to the book's imagery as possible. You can design your visual graphics in color or in black and white.
Label the backs of your index cards. Keep them in order so that you know to which scene or segment of the book they correspond.
Paste the index cards in order on a large piece of poster board. Leave 2 inches between each row of cards.
Fill in the spaces underneath the cards with summaries of the action. This serves as a caption for the image. Keep the summary captions short and simple -- they give viewers an idea of what is happening in the scene.