The documentation and installation instructions for Zimbra describe the process far better than I could, not to mention in much greater detail. I think you should download the install guide & manual and read them... There are 12 pages of instructions covering Hardware requirements, partitioning the system, port numbers, what the various configuration options you will see during install mean, What packages and package versions need to be installed or removed from your system prior to installing Zimbra. I certainly am not going to try and recreate all that in a post here..
Sorry but my answer has to be RTFM.