You add your backgrounds and topper to your site by clicking
on Images on the left side of your store administration
screen.
1).Click on "Images"
2).Click on "Show Images"
3).Click on "browse" at the bottom of the page
4).Select the image you would like to upload and open
5).Click "Add"
To add your buttons you will use the Nav Image for each page and category and this will be where you upload your buttons.