Windows Event Log Monitoring with Windows RM

I downloaded and installed Microsoft Windows ZenPack v.2.1.2, and got everything running, and working fine. The whole reason I was trying to do this, was to get Windows Event log alerts via email. In the wiki, there's a section that says:

To monitor EventLog events you should add to monitoring template with "Windows EventLog" datasource. For the Event Log field put the name of event log (e.g. "System") that you are interested in, and in the EventQuery you could put the filter for events. Filter is written as PowerShell scriptblock for Where-Object commandlet.

For example, here is Event Query for error events only:
{ $$_.EntryType -eq 'Error' }

But I don't understand how to make this work. I can see where you add the data source, but exactly how to get all the details filled out to actually monitor a specific windows event, I don't know... Taking the example, how would I monitor the "System" event log for errors only What event class would I tie it to What's an "Event Key"

Thanks,