First you have to create a freemarker.template.Configuration instance and adjust its settings. A Configuration instance is a central place to store the application level settings of FreeMarker. Also, it deals with the creation and caching of pre-parsed templates.
Probably you will do it only once at the beginning of the application (possibly servlet) life-cycle:
From now you should use this single configuration instance (i.e., its a singleton). Note however that if a system has multiple independent components that use FreeMarker, then of course they will use their own private Configuration instances. Do not needlessly re-create configuration instances; it's expensive as you lose the caches.