You'll have a directory/folder called webclip-manager, put this into your plugin directory.
Go to your admin panel and activate the plugin.
Now go to Options -> Webclip Mgr
Enter the location of your Webclip image. It may be in any of several formats: ico, gif, or jpg. There's no restriction on its name or location, other than that it's a valid and reachable URI.You can always come back here and change this whenever you wish.
Changing your theme or upgrading WP will not affect this icon.