should I install composer for symfony 3 , or it is auto instal when I was instaling symfony? How can I auto generate formula in symfony, I saw that on sympfony 2 and by using cmd.window but how can I do it using 3 version, and what should I have to instal. I have eclipse neon for PHP and I download symfony project inside it. How looks like the procedure to create form?
You will have to install composer yourself, just once.
To learn how to create forms in Symfony: https://symfony.com/doc/current/forms.html