Hello,
WordPress themes are translated the way that is described in the post that you’ve seen. It’s universal for all themes that have been created following the WP standards (incl. this one) and is not specific to the Storyteller theme. That post has a solution.
Basically the solution is:
1. Install Loco Translate plugin.
2. Translate the strings.
3. Make sure site language is set to the language you need.
You can also translate the strings using another tool (like Poedit), however I believe the easiest free way is to use Loco Translate. Regardless of the tool you use it all boils down to translating the strings from the language file.
If you don’t feel confident about implementing this solution, please consider contracting a WP expert to do that for you. You can do that at a number of places online, e.g. Codeable.io.