Graphite configure and startup with NAV 4.0.1

Please, someone can help me to configure and start graphite on Debian 7 with Nav 4.0.1? I already activated carbon setting CARBON_CACHE_ENABLED=true in the file /etc/default/graphite-carbon ENABLE_UDP_LISTENER = True in the file /etc/carbon/carbon.conf But I don't understand how to correclty configure graphite for NAV. Any help will be appreciated. Davide.