There are some sites that won't let you reference clipart directly from their site. Geocities is one of those. You would need to copy over the images to another site and use the address from that site. You can get your own DIS web site on which to store clipart if you like. That is sometimes the easiest and most foolproof way to always keep access to the images you want to use.
Here is a link to some "tutorials". One covers getting a DIS web page and uploading images to it.