Some might get upset about this, but hey editing is art. The process is simple enough. Leaves are generally green, so we just need to change green to orange yellow or red. Luckily Photoshop has just the tool for this. First open up your image. Then open up the raw editor, (CTRL SHIFT A).
Next up drag the sliders for red and orange all the way to the right, and yellow and green all the way left. And thats it! Green leaves are now fall colors!
Hope that helps you get those perfect fall colors on your next photo project!