The advanced features allow the user to customize fonts and colors of Page Text, Backgrounds, Links, Blog Title, Tabs Text, Tabs Background, Date Header, Post Title, Post Background, Gadget Title Color, Gadget Text, Gadget Links, Sidebar Background and to add custom CSS.
A link at the top of the Add CSS screen leads to the help section of Blogger, where you can learn things such as how to add a custom background image.
While it takes a little time and effort to come up with a truly original design in the new Blogger Template Designer, it beats the old template selection hands down.