Hello Enrico!
I was in your situation about half an year ago. I think that it is good to start JavaEE with oracle official tutorial
http://docs.oracle.com/javaee/6/tutorial/doc/javaeetutorial6.pdf
Why?
It is big!
It gives short, basic overview of main JavaEE technologies which are all followed by simple examples !
Finally at the end you are presented with two web applications and one big (as for beginner) enterprise application.
Applications are really useful because they cover all of what you learned throught the book.
These case studies can give you good ground to start doing your own webapp
If you are planning to go further with JSF you should read four series of JSF for nonbelievers.
I myself covered the book on JSF 'The complete reference of JSF2.0'. It seems to me that this was not worthy.
Better to develop with extension of JSF like RichFaces. It is much easier !!!
I decided to do my webapp with plain JSF and I should say it does not look as good as it could be with built-in components of RichFaces
Finally many people (like Tim Holloway) use Spring. Tutorial I recommended does not cover Spring at all ! Instead it covers
EJB !
The best way to study is to develop your own webapp!