First, you're not skinning your today screen, it's a theme.
That will help when you look for themes.
You don't want to skin your top and bottom bars, you want to use a theme.
Skinning is where you change the whole look of a program and you have to edit all sorts of images and different things like that.
WM5 doesn't (normally) allow you to have certain colors for you top and bottom bar.
If you do a search, you can find threads like this one,
http://www.aximsite.com/boards/showthread.php?t=116325, that tell you how to get what you want.
That should be a good thread to get you started. it has links to other threads too.