Do you have Symantec Backup Exec or do you have Yosemite Backup?
If it really is Symantec Backup Exec, then use the CD labeled "Symantec Backup Exec for Windows Servers" to install the product. There autorun program will open up the installer. Just follow the instructions - There should be a link on the dialog to "Install Symantec Backup Exec" The setup is pretty easy.
The documentation (Quick Install Guide) is on the CD in the "WINNT\INSTALL\DOCS" folder.