I don't really have any unanswered questions about "The Yellow Wallpaper," and if I did I couldn't really answer this question for you. My questions would probably not match yours. All you need to do is read the story and see what unanswered questions you have when you've finished.
My guess is that you might have questions about what the woman is suffering from, what exactly she sees in the patterns in the wallpaper, what is the meaning of her circling the room at the close of the story, and what does the future hold for her.
You also might wonder if her husband is okay. But, again, simply read the story and see what questions you have.