Don't get beatup or ignored.
Often times obvious questions go unanswered or a RTFM comment or similar.
Anyhow, my friend, I was once not knowing.
So, don't be afraid to look around at the documentation, its a gold mine.
Anyway, these links below should assist
Documentation for the open source Zimbra Collaboration Suite; email, contacts, and group calendaring
3 out of 2 people have truble wit inglish and fraktions
Intel Quad Core Xeon CPU 3.20GHz | 2 Gig RAM | Dual SCSI 73 Gig HDD
Ubuntu Server 12.04.1 LTS 64 bit | Release 8.0.2_GA_5569 (build 20121210115059) UBUNTU12_64 FOSS