Here's one more way without selecting...with your image open click adjustments, hue and saturation. From the dropdown list pick any color, then take your mouse and click on the color you want to change. The dropdown list will automatically change to the appropriate color. Then adjust the sliders to change the color as you please. Click OK. If you want to change other colors do it again.
As you can see, there are many way to accomplish the same task in Photoshop. It's simply a matter of deciding which works best for you and the situation.