The most common reason why you do not see this button is that you have the StarMessage Special Edition which comes without this button.
You can easily see which version you have:
1) Go to the configuration screen of the screensaver.
[START] (the start button of windows)
-> [Control panel]
-> [Display]
-> [Screen saver]
-> press [Settings]
2) Look at the title of the window, it should say something like:
StarMessage v3.1 Trial
or
StarMessage v3.1
or
StarMessage v3.1 Special Edition
If you have the Special Edition, download the latest free trial from the homepage and put the activation code from the configuration screen.