Have FUN!
Open you image in Photoshop
I aim to make everything black and white except egg York
Double click on the lock in layer palette to unlock the layer
Name the Layer as you desire then click OK - Now the Layer is unlocked
Then go to Image - Adjustments - Hue and Saturation
Drag Saturation to -100 then click OK, the whole image will now be black and white
Grab History Tool and start painting on the York of the egg once done save your image
Then you are done, as simple as that