Customizing forms

Hi! Sorry if this post is duplicated, I was looking for the search function but I didn't found it :(

I'm working with Alfresco Community 5.1, and I need to create a full custom workflow with its own form in Alfresco task's manager. Create the workflow with Eclipse's plugin is easy, but I don't know how to create a custom form with my own input fields for this task.

I'm reading the docs form Alfresco Community, but I have a lot of doubts with it... Does anyone know or recommend any guide that I can use?

Thanks.