Changing An Image's Background Color
This tutorial will show you how to change the background color of an image with a solid background. It works on any of the colors within the image.
1. Open your image. You may want to edit beforehand.
2. Go to the Hue/Saturation tool. (Top navigation bar Layer -> New Adjustment Layer -> Hue/Saturation.)
3. Choose a color from the drop down list that is the same color as your background (green = green, blue = blue).
4. Click on the eye dropper and select the background color.
5. Slide the Hue bar (rainbow bar) back and forth until you get your desired color. You can also change the vibrance on this step.
6. If the Hue/Saturation layer makes any unwanted changes, click on the paint brush tool and set the color to black. Then go over the areas you don't want changed.
Note: make sure the Hue/Saturation layer and it's mask is selected or else it won't work.
When you've reached your desired color, you're done.