How can I create custom form element with custom validator?

How can I create custom form element with custom validator?

i am trying to create custom form element with custom validator. I have
read
http://framework.zend.com/manual/2.2/en/modules/zend.form.advanced-use-of-forms.html.
But i'm Vietnamese and i have work with Zend for 2 months so i can't
understand how to create this type of form. Help me!