Above, these components.
Give an example for each component. Is there such a website, or book?
Yes
See these Built-in Blocks Documentation
Component Documentation
(Anke pointed to one of them)
and
read the ebook described in these resources which can help you learn to use the AI2 tools. A very good way to learn App Inventor is to read the free Inventor's Manual here in the AI2 free online eBook http://www.appinventor.org/book2 ... the links are at the bottom of the Web page. The book 'teaches' users how to program with AI2 blocks.
There is a free programming course here http://www.appinventor.org/content/CourseInABox/Intro and the aia files for the projects in the book are here: http://www.appinventor.org/bookFiles
How to do a lot of basic things with App Inventor are described here: http://www.appinventor.org/content/howDoYou/eventHandling .
Also look here http://kio4.com/appinventor/index.htm and here http://www.imagnity.com/tutorial-index/ for more tutorials.
Learn about components http://ai2.appinventor.mit.edu.ezproxy.canberra.edu.au/reference/components/
and visit the Library http://appinventor.mit.edu.ezproxy.canberra.edu.au/explore/library Help>Library on the MENU