If you are looking for a background, then it's actually quite simple. After reading another post here on the blog forum, I went to
The Cutest Blog on the Block and picked one of their free backgrounds. I copied the html code and, in the layout section (of Blogger) added an html gadget and copied the code there. The first one didn't work for me, so I deleted it and tried again. It was more time consuming to look through everything they had available and choose one than it was to install it.
After having that up, I had my sister, a graphic designer, make me a new banner to coordinate with the colors.
Good luck!