The author of “The Yellow Wallpaper” is describing the life of middle class women in the late nineteenth century. This was a time when women had very little control over their own lives and they had to do what they were told to do, as though they were children, not adults. They were not provided with the same education as men and were discouraged from doing anything that was not approved by their husbands. This was very frustrating for women and because they were treated so unfairly, they were extremely unhappy. If they stood up to their husbands or acted unhappy, they were subjected to “treatments” that were frightening and not at all effective. These “treatments” made the situation worse for women and their mental health suffered. Gilman wrote this story after she herself had been exposed to one of these treatments in which she was told that writing was not good for her. This only made her feel worse because after all, she was a writer! Gilman wrote this story to expose the truth about the ineffectiveness of these “treatments” and even sent a copy of the story to her doctor. Gilman and the narrator of the story are basically the same person and share the same attitudes. Gilman and the narrator of the story are pointing out that women are better off and certainly healthier when they are allowed to pursue their own interests and given equal opportunities in life.
Narrator's attitude is the attitude that the narrator takes towards events and characters in a literary work. Note that this has to do specifically with only the narrator and events that happen in the story. For example, as I see you have read "The Yellow Wallpaper", the narrator in this work is the woman who is writing the journal entries. Her attitude towards her husband and the situation she is in is anger and frustration. She is fearful and paranoid about her husband analyzing and diagnosing her.
Author's tone, on the other hand, is the author's attitudes towards the subject and audience in a litary work. We could also say that this is the point that the author is hoping to make by writing this story. For example, the author's tone in "The Yellow Wallpaper" is full of anxiety and depression. This is used to make a point about how dependent women were on men in the time period this story takes place in (late 19th century).
I hope this helps!