Clipart images are widely available for the grabbing: do a search for 'clipart' in any search engine, and you will come up with a great number of pages.

A couple of reminders:

• use clipart judiciously; much of it, especially the so-called animated .gifs, can be extremely annoying!
• be cautious when applying a background image to your page: don't let the image overwhelm the content
• only use images that are in the public domain!

Have fun (?)