My Blog´s address is this:
http://geistreich78.info/

I´d like to have a Menu like in the Sample preview:
http://test.bytesforall.com/sample-page/

Under "News" you see a dynamic Drop-Down. In my blog there should be the same, when you click on "About". It should disply for example the site "Impressum".

How can I make this happen?

have you defined Impressum to be a sub page of About? this is done in the wordpress page editor

yes. I defined under "Sites" that "Impressum" is parented by "About". But that doesn´t change anything

In >Design > Menues it says:
Your Themes supports 2 Menues.
Choose which Menu should have a certain Position...

and I don´t know what to do here...