You will need to determine which version of Community Server you are running when you want to upgrade Community Server or install the latest Community Server service pack.
You should back up all of your existing files before launching the Community Server 2008 upgrade tool.
You cannot upgrade directly from Community 2007 to Community Server 2008. If you do not have Community Server 2007.1 installed, you must first upgrade to Community Server 2007.1, then from 2007.1 to 2008. To upgrade to Community Server 2007.1, go to http://get.communityserver.com/download/cs20071up.