How do I make my own book of shadows(witchcraft book)?

First, Witchcraft is not Wicca and vice versa. Wicca is a religion focusing on the worship of Gods. Witchcraft has no Gods to worship as it is a practice, not a religion.

A Book of Shadows is not a Witchcraft book. It's a Wiccan book. Sure many Witches may make their own book, but it was primarily created as a book to be used to store important information regarding the Wiccan's practices. The Book of Shadows is also not a journal. One may include a journal in it, but that doesn't make the book itself a journal.

You make your book by purchasing or creating your own notebook. In there you put anything you feel will benefit you on your Wiccan path, For example, a copy of the Wiccan Rede (which, by the way is only Eight words, not a lengthy poem, starting "Bide the Wiccan Law ye must". That was created by Gwen Thomas in the '70's) along with an explanation and history of its use. You can also include rituals for Esbats and Sabbats, prayers to the Gods, circle castings, etc.

If you *choose* to practice Witchcraft alongside Wicca, then you may include other elements of Witchcraft including correspondences used to create your own spells and such, spells, divinitory practices, etc. But these are not necessary.

This might help get you started:

http://theunbeathenpathsbookofshadows.blogspot.ca/...

Start it off as a journal, talk about how you started on the path to witchcraft. Once you start your practice wright down what rituals you liked, what worked, any spells your fond of and just thoughts in general. However I suggest having 2 copies. Use one as sort of a rough draft where you wright things down as they happen, then you can organize it all in the second.

Why waste your time making one when you can just buy it?