I'm Miranda, and I'll be happy to help you with your question.
The wallpaper you selected is quite lovely and elegant. It has a bit of an old-world feel to me, which I love. I would suggest a solid-colored area rug because I think a patterned rug would detract from the wallpaper, and it might make the room look too "busy."
Also, I would suggest not choosing an area rug that is too large because you don't want to lose too much of those beautiful hardwood floors.
I would suggest an area rug with a "neutral" color that will go with everything else in the room but not overpower it. Another factor to consider is how much natural light you get in the room. If you have a lot of natural light, you could go with a darker color for the rug, perhaps a dark gray or dark brown. However, if you don't have a lot of natural light, you should probably go with a lighter color to complement the olive green sofa and the darker room, perhaps a beige, tan, or lighter brown.
I hope that answered your question. If you have further questions, please ask. It's been my pleasure helping you. Please remember to rate my answer positively, as rating me is the only way I receive payment/credit for my work.