Class DatabaseSeeder does not exist

You need a file called DatabaseSeeder.php in your database/seeds-Folder.

This is an example, that comes with a fresh laravel-installation:

<?php
use Illuminate\Database\Seeder;
class DatabaseSeeder extends Seeder
{
    /**
     * Run the database seeds.
     *
     * @return void
     */
    public function run()
    {
        // $this->call(UsersTableSeeder::class);
    }
}

In this file you set up your seed-process (which seeders should be called and in which order)

Yes I found that Thank you for help.

Remember that you have to call

composer dump-autoload

when you add your own seeder classes (e.g. UsersTableSeeder::class,).

See https://laravel.com/docs/master/seeding#running-seeders