Using Color Range to select and change

1, Open image and copy the background

2. use the oval marquee tool to select a part of the image ( in this case, the sky).... this just narrows down the area photoshop has to look at

3. choose Select.... Color Range

4. Use the eyedropper to select the area of color you want ( it helps if the area is a uniform color but use the slider bar to widen or narrow the range you want

5. create a layer mask

6. use the adjustments window to make whatever changes you want

before

after