This theme comes with the option to add dummy content to it, to make it look almost like the live preview that can be found on ThemeForest.
To use this feature go through Tools -> Import and click on "WordPress" (you may need to install the WordPress Importer plugin).
Now you can choose the file included in the main zip file under the folder "dummy content" called
Metropolis dummy content.xml and click "Upload file and Import".
Remember that using the dummy content is not mandatory, still you may find it useful as it contains all the posts, tags, categories, menus and some theme settings from the live preview.
It doesn’t contain sidebar widgets, footer widgets and images.
After importing sample content you still have to configure the theme and to manually create some things like the footer and the sidebars.
Once you’re done, you can take a look how things are set up and use the dummy content as a starting point for your own content. That should make it much easier for you to use the theme, especially if you are new to WordPress.