How to make my website look like the demo without using quic

How can I make my website look like the demo with an installation of Joomla already on the site? I'm not starting a website from the beginning, but want everything loaded as if I did the quickstart.

There is no strict tutorial - that is why quickinstall was created.
But in your case, I would take quickinstall, install it in some subfolder and then go module by module, setting by setting, menu item by menu item to check all settings and apply them to your live site.

Well darn, okay thank you for your help.