Classic CMS are installed in a FTP directory which is also used to store images. Webservice CMS usually don't give a file directory access and offer instead to upload the images. Blogger does to but to use those images in the HTML code, you need to employ a little trick.
One way is to publish an article with all the neccessary images uploaded. Or to create a second blogger site, which is basically used to develop, test and store your HTML blogger template. And you use this template blogger site to upload all your images.
Or you directly use a photo / image publishing service such as Google's
Picasa,
Flickr or
Photobucket to name just a few. Using those services each uploaded picture gets a URL which you can then use for your CSS HTML code in Blogger.
But be aware, in the summer of 2009 we have experienced a slightly inconsisten display of imgaes hosted on blogger and picasa. Google seemed not always load all images.
We therefore used flickr, which for now has never shown any problem. But of course you can use any kind of photo service on the web as long as it gives you a URL for each graphic element.