Change background color behind fabric iPad Ps

You could use a Gradient Map adjustment layer.

I sampled the darker red color and the orange color, applied the Gradient Map adjustment layer (click on the middle icon at the bottom of the Layers panel and select Gradient Map... or go to Layer > New Adjustment Layer > Gradient Map...). Then I clicked on the Gradient thumbnail in the Layers panel and clicked on the gradient in the Properties panel to open the Gradient editor. I set the gradient to Foreground to Background in the Basics preset folder and then added a blue color stop. I moved the orange color stop and adjusted the diamond between the orange and blue.