First Project Creation

After installation we should to install .httaccess file 

composer require symfony/appache-pack

If you use in local development open Server you should write next configuration.

In file Apache_2.4-PHP_8.0-8.1_vhost.conf or enother that your wor, next text

C:\ospanel\userdata\config\Apache_2.4-PHP_8.0-8.1_vhost.conf

<VirtualHost *:80>
DocumentRoot "C:\ospanel\domains\sym.loc\public"
ServerName "sym.loc"
ServerAlias "sym.loc"
</VirtualHost>

After if you planing to use annotations you should install them.

composer require annotations

After if you planning to use templates install twig 

composer require twig

Custom project

config\routes.yaml

app_lucky_number:
    path: /lucky/number
    controller: App\Controller\LuckyController:number

controllers:
    resource: ../src/Controller/
    type: annotation

kernel:
    resource: ../src/Kernel.php
    type: annotation

src\Controller\CatalogController.php

<?php
namespace App\Controller;

use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Routing\Annotation\Route;
use Sensio\Bundle\FrameworkExtraBundle\Configuration\Method;
use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;

class CatalogController extends AbstractController{
    #[Route('/blog', name: 'blog_list')]
    public function list(): Response
    {
        return $this->render('my/index.html.twig', array("mydata" => "Timur"));
    }

    #[Route('/blog2')]
    public function list2(): Response
    {
        return $this->render('my/index.html.twig', array("mydata" => "Timur2"));
    }

    /*composer require annotations*/
    /**
     * @Route("/blog3")
     */
    public function list3(): Response
    {
        return $this->render('my/index.html.twig', array("mydata" => "Timur3"));
    }

}

src\Controller\LuckyController.php

<?php
namespace App\Controller;

//use http\Env\Response;
use Symfony\Component\HttpFoundation\Response;

class LuckyController{
    public function number(){
        $number = random_int(0, 2000);
        return new Response("Lucky:".$number);
    }
}

templates\my\index.html.twig

{# Comment #}
{{ mydata }}

To debug you could use next commands

php bin/console  - shows all commands
php bin/console debug:router - show all routes

php bin/console debug:router --show-controllers --env=ENV  - show all controllers
php bin/console router:match /blog - show route about information

Install debug panel

composer require --dev profiler