You can change the Layer background-
USING NEW DOCUMENT MENU -Usually, when you create a new document in Photoshop, it fills the background with white. But you could easily change the background color right here, in the New Document menu. Just select the color you want from the Background Contents list.
Or open the Color Picker and select any color you like!
USING FILL FUNCTION- If you want to change the Photoshop background color back to white, in the document we've created, you could use this simple method: go to Edit > Fill (or press Shift-F5) and select the white color.
USING FILL LAYER-
- You could also use a fill layer to change your Photoshop background color. Go to Layer > New Fill Layer > Solid Color. Once you hit OK, you will see a Color Picker, where you can select any color you want to use.
- Use a solid color fill layer as a background, because you could easily change its color just by Double-Clicking on it in the Layers panel.
CHANGE THE BACKROUND COLOR OF A PHOTO
- To change the picture's background color, we will use the Quick Selection Tool, which you can find in the Tools menu. Start selecting the objects on the photo (or just click Select Subject in the latest version of Photoshop).
Polish the selection using the Quick Selection Tool, while holding Alt.
- Press Shift-Control-I to invert the selection.
- Create a Solid Color Fill layer and select the color you want to use for the background.
- Change the Blending Mode of the Color Fill layer to Multiply and play with the Opacity until you get the best result.