My dd birthday is coming up and she wants the barbie doll cake can someone please tell me how to do this or where i can find instructions on how to do this.. thanks

Here are some links to other threads on doll cakes. There is some good information here. They should help:
http://forum.cakecentral.com/cake-decorating-ftopict-592523-doll.html
http://forum.cakecentral.com/cake-decorating-ftopict-595306-doll.html
http://forum.cakecentral.com/cake-decorating-ftopict-594189-doll.html
http://forum.cakecentral.com/cake-decorating-ftopict-589225-doll.html
http://forum.cakecentral.com/cake-decorating-ftopict-590378-doll.htmlhttp://forum.cakecentral.com/cake-decorating-ftopict-591176-doll.html