To access Trac for the first time, you will need to go to the Project page of the project for which you activated Trac, and then select the Actions > Open Trac link. For future use, just bookmark this page so you don't have to go through the CloudForge interface every time.
User and Admin Guides
Trac is a well established OpenSource project with existing documentation. Please take a look at the official Trac Guide http://trac.edgewall.org/wiki/0.12/TracGuide
More info on Trac:
- The Trac Homepage http://trac.edgewall.org/
- Wikipedia's Trac Article http://en.wikipedia.org/wiki/Trac