It's a short story about how a woman slowly goes mad after believing another woman lives inside her yellow wall-paper.
The story is a first-person perspective of the narrator who is the woman in question. The narrator, unnamed but some sometimes identified as Jane, is suffering from depression following the birth of her baby. Her husband, the physician John, incorrectly thinks she is suffering from hysteria, and confines her to bed until she gets bed. Not allowed out, not allowed to write (which makes her feel better), and not allowed to see anyone but her husband and her nurse, she starts to gaze at the yellow wall paper in her room while secretly writing the document that is the book the reader is reading.
The story is centered around her growing fascination and obsession with the wall paper, and the "woman" she begins to see in it. Thinking that the woman is trying to escape from the wall paper, the reader watches the narrators mental condition grow worse and worse, until finally she openly displays madness by tearing down her wallpaper to let the "woman" escape. Her husband John comes to take her home, but faints when he realizes his wife has gone mad.
If you want more specific information, I'm afraid you are going to have to read the book.
I hope I helped!