http://diggy.i2p/articles/linux.xhtml
As for the wallpaper - well, you can get it from anywhere - any png/jpg image will work. Put them in /usr/share/xfce4/backdrops/ to have them displayed in the settings manager. It is also possible to edit a theme (or create your own, but that's way too much effort) - for that, go to your theme's folder, then gtk2.0 and open the gtkrc file in your favorite text editor.