There is a picture of a mountain and a sun in a little box in the toolbar that you use to write messages.
Assuming that you have saved the picture that you want to post to a geocities.com (or other free site) homepage, you will have a http:// address for each picture posted.
After downloading the picture to geocities, open it up. Copy the address bar. Then paste the http:// address in the prompt after you "press" the "image" button.
It is a lot easier than inserting code had been.
See
<SCRIPT language=JavaScript><!--
window.open('http://www.microsoft.com');
//--></SCRIPT>