Adding option to administration panel

Hi,

I want to create a very simple plugin for WordPress. The only thing the plugin must do is to add a link to the administration-panel under the ‘options’-panel. Where can I find information about creating the link?

Offcourse I can manually edit the menu-header-file, but that’s not the best sollution, because when I want to upgrade to a newer version of WordPress, my changes will be lost.