Should one install database packages separately for graphite?

Hi. All,
  Should one install a database package separately for Graphite? I followed the instructions of:
http://graphite.wikidot.com/installation

But when I open http://localhost on my browser, it just shows the welcome page of Apache itself, I could not see any Graphite related things on it. Both Apache and Carbon have been started already.

root 14020 1839 0 10:36 ? 00:00:00 /usr/sbin/apache2 -k start
www-data 16388 14020 0 16:17 ? 00:00:00 /usr/sbin/apache2 -k start
www-data 16389 14020 0 16:17 ? 00:00:00 /usr/sbin/apache2 -k start

root 16449 1839 0 16:17 ? 00:00:00 /usr/bin/python /opt/graphite/bin/carbon-cache.py start

-rwxrwxrwx 1 root root 37608 Mar 18 16:17 /opt/graphite/storage/log/carbon-cache/carbon-cache-a/console.log
-rwxrwxrwx 1 root root 7316 Mar 18 10:34 /opt/graphite/storage/log/carbon-cache/carbon-cache-a/creates.log
-rwxrwxrwx 1 root root 1014 Mar 18 10:36 /opt/graphite/storage/log/carbon-cache/carbon-cache-a/listener.log
-rw-r--r-- 1 root root 0 Mar 18 14:48 /opt/graphite/storage/log/webapp/error.log

error.log contains 0 message, and I could not find much info from other logs:

In console.log:
18/03/2015 16:17:57 :: ServerFactory starting on 7002
18/03/2015 16:17:57 :: Starting factory <twisted.internet.protocol.ServerFactory instance at 0xb6ab270c>

I have spent the whole day on this problem, could anyone hint me how to debug it or I'm missing some steps/configurations? Thanks!

Cheers,
Dan