Hello Mark,
You need to create 2 tokens in the plugin configuration.
#1 : REGISTERED for Registered usergroup
#2 : PRIVATE for Private usergroup.
then use
{f90filter REGISTERED SHOW}Content to be displayed to Registered usergroup{/f90filter}
{f90filter PRIVATE SHOW}Content to be displayed to Private usergroup{/f90filter}
Hope it helps. You can check more detail at our documentation
www.function90.com/docs/content-filter.html