The picture at the top you can add right in the welcome_txt language variable, or in customer/main/welcome.tpl. You can add a different image for each category by adding the image to the category description.
The items on the right are just plain old images, you simply add them to the third column in customer/home.tpl. To call an image, just put it in the skin1/images directory and call it like this:
<img src="{$ImagesDir}/imagename.jpg" alt="" />