Can some help me with the steps to upgrade an exsiting Alfresco installation Version :Community - v3.2.0 (2039) to the latest Alfresco 3.4.a Community version ?
Try going directly. Just follow the procedure here http://wiki.alfresco.com/wiki/General_Upgrade_Process It is in the wiki article, but again: Make sure you have a working setup of a default Alfresco of the version you want to upgrade to. Then apply your backups (becuase you did backup, right?).
So fist try is 3.2.0 -> 3.4.a If that fails, try doing the upgrade with intermediate steps, like 3.2.0 -> 3.3g -> 3.4.a
If you make all the proper testing, and take notes of every step for an upgrade, your production upgrade will run very smoothly.