Dear Reinhard and WeatherCat scripters,
I found it here: Script-Editor > File > Open Dictitonary > Choose System Events > Scroll down to Screen Saver Suite
But as said before, I do not know what to do from here on.
Alas, knowing AppleScript wouldn't have helped you anyway. All you can do in AppleScript is to start or stop a screen saver, you can change which screen saver is running and you can set the general preferences. There is no way to display any text.
Oh well, it was a good thought!