How do I photoshop this picture?

I have a friend that has a missing tooth on the side and she is very self consious about it. The other day we took a picture of her and she looks absolutely beautiful in it, but you can see where her tooth was pulled on the side. We were talking and thought it would be funny to photoshop it to where she has a blinging fake gold tooth with a diamond in it! Does anyone know how to do this?How do I photoshop this picture?
Ok First thing is that you have to open the picture. Next you need to get a picture of gold your a real gold teeth from browser images. Next you extract the image in Filters---%26gt; Extract, extract the picture with the brush by coloring the outside of the object. Then fill it with the paint can until the image is filled in with the color, then click ok. You will get the object on a diff window. Pull the image to your friends picture. Move the image around to where you want it. After that you do what ever with it.