You need to be more specific. do you mean multiple pages of data or multiple fixed pages in a single report? In general reports are not meant to print lots of fields only lots of data. Stretching reports across multple pages can be probablmatic but you can try using the sliding when printing feature but it will not respect page break. In 11 I think the limit was 11 pages pages not sure about 12.
I mean they write a very long text inside a single field. The text arrive at 3/4 pages when printed, so I have only one field in the report that should go further than one page and the lenght is variable.
Further I should also prepare a multiple field report where I will put a portal in the body layout but what can I do if I have to handle 60/70 records?
Single fields don't stretch over one page very well you can do it and use sliding but it won't page break properly. You could export the data as XML for use in a Word document hten you wouldn't have page break issues. If it's just one field you also just export out the text unless you need to keep the formatting.
Suggest you do a search of threads on this site re "Virtual List" reporting, which has been written up at least a couple of times, and is covered on some other referenced sites. Virtual List reporting allows you to break out paragraphs or lines of text from one record as multiple "reporting records" into another reporting table so that you can print any length report needed based on the line/paragraph records as a list-view layout rather than having to design for a single-record form-view layout. And it can cleanly break across any number of pages.