4laugh thanks!
Anyway, here's a short gradient tutorial for you. Color fades are way easy:

1. Shade the dress all the same color first (in your case, it's sort of a light red). Make sure all the shadows and highlights are in place. Duplicate the layer with the dress.

2. Adjust the hue and saturation (and maybe the brightness and contrast) on the duplicate layer until the whole duplicate is the other color (purplish).

3. Take a large, soft-edged eraser and erase the parts of the dress that are meant to be the first color.
See? Easy as pie! This method will work for whatever two colors you want, in any pattern (though for more complicated patterns, you may want to use a layer mask instead of the eraser).