It feels to me that “this is not helpful” means here “I don’t know how to do that”.
Please read our official guide: Beginner's guide to developing Discourse Themes.
There are several ways to overrides templates (which is a solution for which you are trying to achieve). One is described in this section: https://meta.discourse.org/t/beginners-guide-to-developing-discourse-themes/93648#overriding-discourse-templates-23