How do I match the background colour with the new image

If the crumpled paper is on its own layer, there are a few techniques for blending it in with the background:

1. Apply a blending mode
   • With the layer selected, go to the top of the Layers panel and change the dropdown menu from Normal to either Overlay or Soft Light (or try out the others to see what works best)
2. Change the opacity
   • With the layer selected, go to the top of the Layers panel and to the right of Opacity, lower the percentage
3. Apply a layer mask to feather the edges
   • With the layer selected, click on the 3rd button from left at the bottom of the Layers panel. Select the layer mask thumbnail and use the brush to apply black where you don't want a part to appear, apply white where you want it to appear, and apply varying shades of gray (as a gradient or with blur applied) where you want to feather portions.
   • You could also select the layer, go to Select > Load Selection and set the current document as the source while creating a new selection, go to Select > Modify > Feather and set the Feather Radius to something fairly large compared to the size of the selection, and then click the add layer mask button to make a layer mask based on the selection.