So, to clarify, the poem is trying to show us the features of a poem, and demonstrate the extent that a poem can go it, but isn't really talking about her or anything about her? Just using that information to show us something that poetry can do?
"This Is a Photograph of Me", as with many of Margaret Atwood's works, is a strongly feminist poem, set in cottage country in Ontario. It is almost a snapshot version of her novel Surfacing, in which the role of women in a patriarchal male society is compared with Canada existing as a neighbor to the United States. It makes an association between the countryside of the Canadian Shield and the feminine we also see in Atwood's The Journals of Susanna Moodie, which in a sense reclaims the narrative of the frontier from the patriarchy.
The main, and extremely powerful, point the poem makes is that even though this is the photograph of a woman, we barely see her. All that remains of her in memory is a generic picture of a cottage by a lake, not the woman herself. The woman has been erased from the historical record. Her suicide is in a sense the ultimate form of complicity with this erasure, a way of completing her disappearance. As Atwood has written widely about this erasure of women in her essays and literary criticism, her main points here are the way that no one really looked at or paid much attention to the woman while she was alive, and her suicide is the ultimate rebuke to patriarchy.
Although this is not primarily a generic poet about poetry -- the eNotes summary is really doing just what Atwood is protesting, erasing the woman as an individual suffering under patriarchy -- it does show that in poetry, as in photographs, we can and should find the traces of women's voices by looking closely, as the narrator recommends we do to the photograph.