Anne Bradstreet never intended for her poetry to be made public, and "The Author to Her Book" talks about that very issue. The speaker metaphorically speaks of her book as her child, and she notes that her friends took her work and published it for all to see.
The language of the first lines is pretty harsh. She calls her work "ill-formed" and "feeble," and says it is dressed only "in rags." Everyone who reads her work can clearly see all of her errors, and she is embarrassed at having her "rambling brat" call her mother.
In lines nine and ten, the speaker admits that she tried to disown her own child (her poetry) because she found it so poorly dressed (written).
I cast thee by as one unfit for light,
The visage was so irksome in my sight,
Line eleven finishes her thought, though, and the word "yet" is clear evidence of some kind of resigned acceptance:
Yet being mine own, at length affection would
Thy blemishes amend, if so I could.
The word "yet," especially in poetry, is an indicator of some kind of change, as noted in aszerdi's answer, above. Though it is not something she is proud of, she has decided that this boy (her poetry) belongs to her and she will do her best to clean it up and make it more presentable to the world. Unfortunately, every time she tries to make an improvement, she only finds more flaws and defects. She discovers that despite her best efforts, she does not have the skill to improve upon her work.
Her final words are a warning to the hapless boy (her book of poetry): beware of the critics and go somewhere where no on e knows you. If anyone asks the boy who is father is, he is to say he did not have one, and if anyone asks about his mother, he is to say that she did her best with him but had to send him out this way nevertheless. In terms of her poetry, this poem is her apology for not being a better, more artful poet. It is ironic that we still read this work more than three centuries later.