How can i use an external form instead of Bonita form?

I have a simple process, that contains 2 HumanTasks. I want to use an external form using html page. I have reviewed this information:
http://documentation.bonitasoft.com/redirect-form-page-external-url

But , as i have the Bonita Comunity 6.5.1 version , i can not do . Likewise , also i did not understood the information that contains the link.

So how can i do it ?

Regards