I defined the form in my page controller.

function SignUpForm() {
       //$field = $this->dataFieldByName('Title');
      
       // Create fields
       $fields = new FieldSet(
         //new TextField($name = "Seminar Name", $title = "Seminar Name", $value = Title),
         new TextField($name = "name", $title = "Name", $value = ""),
         new TextField($name = "company_name", $title = "Company Name"),
         new TextField($name = "phone_number", $title = "Phone Number"),
         new TextField($name = "email", $title = "Email"),
         new HiddenField ($name = "Seminar_Name", $value = "???????")
       );
      
      
       // Create actions
       $actions = new FieldSet(
       new FormAction('doSignUp', 'Sing Up')
       );
      
       return new Form($this, 'SignUpForm', $fields, $actions);
   }

My hidden field is supposed to have the title of the page as value.

I tried to do like this:
$field = $this->dataFieldByName('Title');
new HiddenField ($name = "Seminar_Name", $field->Title)

but it doesn't work.

Also some fields are supposed to be required. How would I do that?

thanks

Thank you