You can add images in headers and footers
Admin -> Style Manager -> Headers and FootersWhen on the Headers and footers page click on whichever field you want to edit; either the header box or footer box.
Then insert this code:
<img src="url" alt="some_text"/>
To get the "url" right click an image and click "Copy image url" then paste it in. Fill in the text with whatever the image is, so when you hover over it you can read what it is.
Hope that helped