At first, thanks very much for your quick and detailed answers.
First point I know now, that Sketchup free Version isn't able to show lights, exept the sun.
I installed the Renderprogram Kerkythea, and tried already placing lights but I get no result, sometimes I have light, sometimes not. And I don't know, why, or where I can change the lumen or anything else (Is it right, that the light effect is only seen after rendering?).
Also i searched alreay in the Internet for a Tutorial, but I don't find anything I understood the context...
I have now a new toolbar (Kerkythea) in Sketchup, with two standard lights and the possibility, some others to import. But I don't know how to use
So I need a short and easy step by step how to manage it.....?
Daisy