[Zope-CMF] How can EASILY add a new custom content Type?

[Paolo Quaglia]

Hi to all
I'm a new user of CMF 1.3
I would like to know how can I Add a new content type or How can I modify an
existing.
In particolar Is there some administration tool t define the structure of a
content: 
for example to specify that the news is composed of these fields:
- date
- title
- abstract
- txt
- author

etc...

I have seen some other content management system and, in these products,
there are some gool administration interface to do this task.

There is any kind of this tool in Zope?

Thanks very much
Paolo