Statue of liberty modifications. how make it look realistically?

Hey there,

I m trying to modify the statue of liberty a little bit but I can't figure out how to make it look realistically. I'm trying to make it look like the statue is wearing nothing. So far I have three layers.
One with the original statue, another one with a little bit of clone stamping, and one with a picture of a nude lady but how do I change the color of the nude lady so that it looks the same as the statue?
(similar to this: hxxp://wxw.freakingnews.com/Statue-of-Liberty-Short-Dress-Pictures-63054.asp)
Replace x with correct letter

Anybody out there who knows how to do this kind of stuff or has a link to a tutorial or at least knows how to call this "effect", so I can look for myself.

Thank you