Welcome. Take a minute to look around the site ... there are alot of apps out there that can help you.
Backgrounds can be changed many ways. The two most popular are by windows mobile themes. some are found here:
http://forum.ppcgeeks.com/showthread...ighlight=theme
Dialer skins are all over the place google "dialer skin windows mobile"
There are a few startmenu programs out there. One is qmenu and its free!
http://www.freewareppc.com/utilities/quickmenu.shtml