Downloaded Drupal 8 with composer, now what? I'm a complete Drupal newbie trying to install Drupal 8 for the first time on a new server.  I downloaded the software following the instructions in section 3.5 of the User Guide, but there doesn't seem to be a next step.  Section 3.6 seems to be an alternate method of downloading, and nothing in 3.7 seems to be a continuation of 3.5.  How do I get back on track?

Further information:  In 3.7, it says to go to the URL I set up for the site.  When I do this, I get an index of the directory with these files and directories in it:

LICENSE
README.md
composer.json
composer.lock
[DIR] drush/
load.environment.php
[DIR]   logs/
phpunit.xml.dist
[DIR]   scripts/
[DIR]   vendor/
[DIR]   web/


I'm installing on Ubuntu 18.04 with Apache 2.4, MariaDB 10.1 and php 7.2.
Composer installs all dependencies for you

Next steps 


setup a database with user and pass
setup so that your apache/nginx see /web as the webroot (revisit/fix this step so you can get on next step)
visiting the URL should bring up the installation procedure which should ask for DB/user/pass, follow the instructions to complete the installation