Endpoint Protection

I am new at this so please be patient.  I ran the Symantec Help tool and it says I need to instal the latest version of Endpoint Protection Manager 12.1.6318.6100.  What does this entail?  Do I have to shut anything down?  Do I need to update any of the clients or just the manager?  Where is the download located as I am having trouble finding it.  Also, do we have to purchase another license for this update?

Thanks for your assistance.
 

The steps are outlined in this article:

Upgrade or migrate to Symantec Endpoint Protection 12.1.6 or 12.1.6.1

• Download the latest version from https://symantec.flexnetoperations.com using your serial number.
• You can upgrade the clients if you wish but it is not required, only recommended and best practice:
  • Steps to prepare computers to install Symantec Endpoint Protection 12.1.x client;
  • Assign client packages to groups in the manager console
• Your current license entitles you to free upgrades.