Simply ...
Your title block template is used for plan production. When you create view frames you specify the sheet template and which layout tab to use (depends on scale, whether plan/pro or just plan, etc.). Later when you create sheets it uses the template for layout tab border and title block.
In your template, title block, you use fields in the places you want to populate with data from the sheet set. Edit the attribute, Insert a Field, and then look for the sheet set category. You can insert sheet set name, subset name, project name, project number, sheet number, etc. as well as custom fields that you define.
when you create sheets you specify which sheet set the sheets are added to and it pulls sheet set property data to populate the title block.
at any time you can edit the sheet set properties, the subset properties or individual sheet properties. Saving the drawing or using UPDATEFIELD will update the title block.
It's really a powerful tool and can save a lot of time and mistakes. I hopefully got you started, but the best way to learn is to start to use it. You might look further into page setups, how to have it point to the correct default plot folder, renumbering/renaming sheets, etc.