Let me start by saying if you are not yet using Redmine for technical project management I highly suggest you start doing so immediately. It is very easy to import Trac projects and with minimal coding efforts you can import from any ticketing system you are currently using.
I am fairly new to Redmine and I just entered a ticket with some incorrect information in the description. After looking around for a bit I was unable to locate where to edit the description as it is a bit hidden. The ability is there to edit the description and subject by following the below instructions.