How do I test template changes in the wiki?

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http://chakra-project.org – I intend to change the "cli" template a litlle bit and read the comment which says:If you want to edit this template, create a template subpage of your user, copy the text and experiment there.Although reading the MediaWiki entries for "Template:subpage", template sandbox- and testing-subpages, I don't really get what I'm supposed to do here. (HowTos)