Change Nautilus user interface

[Projet Fe <projet_fe yahoo com>]

Hello everybody, excuse my bad _expression_ I dont usualy speak english. For a school project I whant to change a little bit the user interface of nautilus. I would like to make it more simple and more beautifull.
I downloaded the source code, and i get lost between 723 files and 20 folders. I tried to find in which one the ui is being constructed but I got nothing. I noticied that some parts of the ui are dynamicaly loaded from XML files. But it is not the parts I want to change. Can you tell me where are loaded the (static) widgets of nautilus ui? And how can I personilize it?