In the previous post we learnt how to create a menu link to access our forms so now we will learn how to create those forms. For our Bingo module, we will need two forms, one to add participants to the contest and other to delete participants from the contest.
Let's start with the form to add participants. We need to implement \Drupal\Core\Form\FormInterface and override it's methods. You can take a look at all available methods in core/lib/Drupal/Core/Form/FormInterface.php file. The following code implements our AddForm class: