In this tutorial, I will show you how to manipulate colors of a particular part of an image. First grab the "Polygonal Marquee Tool" from the toolbar and create a selection around the part of the image you wish to manipulate. Once the selection has been made, create a new layer and hit "Delete" on your keyboard. Fig 1 shows the results of my demonstration with just the top layer showing.
Original
Selection Made
Make sure you are on the layer in which you wish to change the color of and go to the main menu bar and select "Image" then "Adjustments" and lastly "Hue/Saturation". Turn the "Saturation" all the way to minus 100 and hit OK.
Here are a couple of examples that I have done.
