Configure Freepbx 2.7 or 2.8beta with fax for asterisk by digium

Hello,
I configured a server with Asterisk and FreePBX 2.7 ( i try also 2.8beta ), I installed the modules:

res_fax_digium-1.6.2.0_1.2.0-i686_32
res_fax-x86_32-1.6.2.0_1.2.0

and from asterisk console I see the modules active.

Someone I can indicate where to find documentation to configure FreePBX to receive faxes?
many thanks.
Oberdan Albertoni.