Well, the first place you could look is the eNotes summary on Homer's Iliad. This contains a book by book summary and analysis of Homer's epic poem.
In eNotes, you can also find a biography of the poet Homer, as well as an introduction to the entire poem and an introduction to the genre (epic) of the poem.
I have found useful the descriptive section divisions that accompany each of the books in A.S. Kline's online translation of the Iliad. See an example at http://www.poetryintranslation.com/PITBR/Greek/Iliad1.htm.
You can also find David Silverman's book-by-book outline of the Iliad on the Reed College website.
One final note: Homer's poem is divided into books, not stanzas. Each line of Homer's poetry is written in a meter called dactylic hexameter.