"The Author to Her Book" is an autobiographical poem in which Bradstreet reflects on the 1650 publication of her collection, The Tenth Muse Lately Sprung Up in America. Of course, the poem also goes beyond the specifics of Bradstreet's situation, forming a broader discussion of the relationship between an artist and their work—a relationship often fraught with difficulty and disappointment.
It's also worth remembering that Anne Bradstreet was one of the first female published poets. Poetry was a gendered environment and much of Bradstreet's early work seems anxious about attaining the standards of male contemporaries. In this poem, though, her appraisal of her own writing seems more intent on the age-old question of whether it's any good.
The poem establishes its mode of address right from the start: apostrophe. The speaker, who in this instance can be fairly equated with Bradstreet herself, talks to her own book—which, of course, can't answer back. The book is personified through an elaborate extended metaphor—also known as a conceit—as an infant child. This, of course, borrows from Bradstreet's own experience as a mother (though by all accounts she was an excellent one!) and as a woman expected to undertake domestic work (and not be wasting time on poetry). The opening line links the weakness of the book to the weakness of Bradsteet's own "feeble brain," gentle /f/ consonance connecting the two together ("ill-formed offspring").
The following lines tell the story—or a story—of Bradstreet's book (it's not known for sure if she wanted it to be published or not). The book was "snatched" by Bradstreet's "friends" (her brother-in-law, John Woodbridge, was responsible for the publication), who took it to England to printed. The poem stresses the book's inferiority, using metaphorical poverty to suggest the Bradstreet's supposedly limited abilities as a writer. That's why the book wears "raggs," and is full of "errors."
The multiple caesurae in this section make the poem clunky and cumbersome, fitting in with the way the book is made to "trudge" to the (printing) "press." Bradstreet self-consciously pre-empts any criticism of her work by making that criticism herself, and asserting that others will feel the same way—"all may Judg" (line 6).