It isn't something you will be able to accomplish using the visual editor. It is writen in code, sometimes in PHP or CSS files as to how to place your graphics. If you have a free site you will not easily accomplish this task.
Clip art is a word processing term and is misleading when people apply it to web pages. All images are the same as far as the web is concerned and adding something descibed as "clip art" is no different to adding a photo.
Whatever editor you are using to build your site will have a standard utility to insert images.
Gwynne, I have looked at your question again, and I sense that you are referring specifically to the free clip-art provided by Bravenet. Unlike the free music clips, there is no "code" per se (such as an "embed" code) which must be inserted at a particular point. Rather, the clip art, as in all images, is identified by a file name and location. When you download Bravenet's clip art to your computer, the next step is to move that file to your website. As others have pointed out, the method for doing this is dependent upon your editor. If you tell us what editor you are using, we can provide further assistance.