Use either of the colors present in the wallpaper. If you take a piece of it to a paint store they should be able to color match it.

If you color match the blue, go for a 30 per cent value. The exact color will be too strong as it reflects off all the walls. That being said again use a lighter version of the pale white color. But.....I like the color of your walls! If I were doing it I would definitely bring in the blue in the wall paper, as my secondary color and use it for 30 per cent of color weight in room. Ie.,possibly in lamps, art work, a rug on 2/3 area of the bed or the whole bed, throw pillows, throws, the curtains....some options to accent the room. Then 10 per cent of accent color; orange, purple, gold, silver black, citron etc. The paper is delightful....really really well done.

Color match the blue in a matte finish or the background color of the wallppaer and use the blue as mentioned for accents. BTW when asking for advice on a space a really good idea is to post pics of the space ,Here in a comment DO NOT start another post.

have you looked at BM Blue Lace?

Agree with either color in the wallpaper. I’d probably go with the background color.