[Plugin: NextGEN Gallery] how to hide pictures

Hi, sorry for my bavarian english.

I want to use nextgengallery but i can’t find a way to have shown just one single thumbnail. On click there should open the Shutter-Thing – and you should be able to go orward and back by the buttons – like it works with [nggalery id=”x”].
But just one Thumbnail sould be seen!!

I read, that there is the possibility to hide some pictures. But How???
I’m screening since hours and can’t find any button to hide a picture.

Thank you for an answer! and please consider, that I’m not good in Languages – neither english nor php etc.
Irmen

http://wordpress.org/extend/plugins/nextgen-gallery/