You may add your new Seeder to the DatabaseSeeder class.
    /**
     * Run the database seeds.
     *
     * @return void
     */
    public function run()
    {
        $this->call(UserTableSeeder::class);
    }
To run a database seeder, use the Artisan command
php artisan db:seed
This will run the DatabaseSeeder class. You can also choose to use the --class= option to manually specify which seeder to run.
*Note, you may need to run composer dumpautoload if your Seeder class cannot be found. This typically happens if you manually create a seeder class instead of using the artisan command.