I don't remember when the web Usage controls was introduced... I'm going to guess 7.0?
To upgrade your box to the the current version, click on System Administration>System Upgrade. Click on the Available Upgrades and see what's available for your hardware. If nothing is there, contact your reseller.
Review the release notes for the version you want to upgrade to. http://www.cisco.com/en/US/products/ps10164/prod_release_notes_list.html
Select the version you want, check the box to save the config, you can also have it email you the config. Make sure to uncheck the "Mask passwords..." so that if you have to reload this config on something, it works properly.
There are a huge number of changes in how web usage control works, and the visibility it gives you into what apps users are using and how those applications work. Far to many to go into here. Look at this document:
Chapter 18. http://www.cisco.com/en/US/docs/security/wsa/wsa7.5/user_guide/WSA_7.5.0_UserGuide.pdfhttp://www.cisco.com/en/US/docs/security/wsa/wsa7.1/user_guide/Cisco_IronPort_AsyncOS_7.1.0_User_Guide_for_Web_Security_Appliances.pdf