With firmware versions 6.6 and Client 6.6.1 and up
Make sure you have a connection to the Processor either using cat5e from your laptop to the laptop port or over your network.
Load the GRIDSMART Client and click the site you want to configure.
Click "Configure" in the pop out menu on the left of the screen
Click "Site Settings" in the "Configure Menu"
You should now be able to set your NTP servers and apply the settings.
For systems running software prior to 6.6, update to 6.7 for NTP support.