Installing Drupal

Hello, I am trying to move Drupal 9 site created with composer on localhost to the web domain, however, I run into problems.

Until now when using drupal7/8 I copied all subfolders and files in the root and move from localhost worked fine.

Now the Drupal 9 structure is

/vendor

/web - In web subdirectory are placed other folders.

When I run the website from localhost it is run http://localhost/sitename/web/. Webhosting does not provide composer or change directory from public_html/web.

I'm trying to set up drupal 9 on my PC (Debian) for local development of several web sites that I plan to publish when they're ready. I want to use the multisite feature of drupal (using the same copy of drupal for each site), but to use different databases for each site.

I think I've successfully installed php7.4, mariadb-server, and phpmyadmin - at least I get no errors when testing apache2, and can log on to phpmyadmin and create users/databases.

So far I've:
    1. Installed apache2, php7.4, mariadb-server, and phpmyadmin,

I'm trying to set up drupal 9 on Debian for local development of several web sites that I plan to publish when they're ready. I want to use the multisite feature of drupal (using the same copy of drupal for each site), but to use different databases for each site.

I think I've successfully installed php7.4, mariadb-server, and phpmyadmin - at least I get no errors when testing apache2, and can log on to phpmyadmin and create users/databases.

So far I've done the following:

    1. Installed apache2, php7.4, mariadb-server, and phpmyadmin,

I'm trying to grow my expertise and learn to use composer. I plan to start by using it locally on MAMP. I've managed to install composer and used it to download the 'recommended project' into a directory named 'my-testing-site'  with the following path: /Users/myusername/my-testingsite. This has generated some questions about placement and order of operations. I apologize for the basic nature of my questions. I've spent the last several days searching and reading and remain confused.

I have a website with Drupal 9 and I want to apply a patch to the "Back to top" module. When I update the module with Composer, the patch is not applied. Why ?

Please help me!!!

I have a centos server with site drupal 7 (PHP5.6) running in.

Now I have to install drupal 8 on this.

I've installed PHP7.2.34 and select this PHP version for the drupal 8 site.

When I run install drupal 8 (v.8.9.16), some errors occurred:

PHP EXTENSIONS

Disabled

Drupal requires you to enable the PHP extensions in the following list (see the system requirements page for more information):