1. Open the below link and make sure that you have met the system requirement for installing SEP 12.1.      http://www.symantec.com/business/support/index?page=content&id=TECH1638062 .Open the CD drive and double click on ‘setup.exe‘. <CD drive>:Setup.exe.3. It will give you an introduction window that these set up file will perform. Click on ‘Next‘.