right well a quick look at the layers pallet...
to make a blank new layer, just click the new layer icon
to make a copy of the original layer, click the copy, then the paste icon
so to make this picture..
open original image, save the image as a new file so you dont ruin the original, copy and paste the layer so there are now 2 layers. Click the 'eye' of the top layer to make that layer invisible for now, and work on the bottom image by clicking on the small picture on that layer.
I have changed the colour of the bear by altering the Hue(I wont go into that in detail, basically select Enhance from the menu and then Hue and Saturation, slide the Hue slider to change the colours)
Make top layer visible by clicking on the eye of that layer, then click on the picture in that layer to make it the working layer
Decide how you want to do the selective colouring, in this case im just going to delete the top layer bits that i want to change colour of, i select them using the magic selector tool and delete the bits i miss with the rubber tool.
i hope that helps a little? Experimentation is the best way forward, i havent used this software before so I dont fully grasp it but it appears to be similar to Photoshop
