Those who are starting now follows a kickstart video
that helped me a lot in the beginning.
Installing Zimbra 8.0.4 on CentOS 6.4 X64 - RHEL 6.4 - YouTube
With the help I installed Zimbra 8.0.7 GA RHEL6_64 on CentOS 6.5
in the Amazon Web Services EC2 for testing.
Hope this helps.