I know there were some posting several years ago similar to what I am asking here but I didn't see any solutions to it so I am going to post the question again and hope someone would know the answers.
How can we log the activities of a user in Alfresco 4.2c, including when the user logged in, which files he/she accessed, created, deleted, modified, etc. ?
what you are looking for is probably <a href="http://wiki.alfresco.com/wiki/Auditing_%28from_V3.4%29">Auditing</a>, which already comes with some standard configurations for activity collection. In terms of processing the data and creating some meaningful reports, you would have to roll your own solution specific to your needs.
You are correct, Auditing is exactly what I need. I can processing the data myself not a problem, I just need to see which tables does Alfresco stores the auditing record and how to configuring the auditing in version 4.2c