Folder structure installing Contao 4.9 on Ubuntu 18 for testing

I will do a testing installation on my QNAP-NAS. I need more specific information about the folder structure for installing Contao 4.9 on a Ubuntu 18.04-server.

I am following this instruction https://websiteforstudents.com/insta...p-7-1-support/

Unfortunately, it is old and does not include the composer installation

I have installed php 7.3 and composer using this instruction https://getcomposer.org/download/ The composer.phar is now located in /var/www/composer.phar

I now need to copy the contao-manager.phar file to the /web folder and make this folder "document root". I do not understand where the /web-folder should be created!
This does not help me as I do not understand where the base of the folder structure is located https://docs.contao.org/books/cookbo...structure.html

Is /var/www/html/contao/web/contao-manager.phar the correct place?

(How can I make /web the document root? I do not have webmine or similar. Only the terminal so I need a linux command.
/edit- I found out how to change the document root. https://askubuntu.com/questions/3378...ary-hard-drive)

/Roland