Access document like document-details - Alfresco

I create a new html page to Alfresco, that shows information when I click on a action library button. In document-details page, we have the "preview" of the document, and what I want to do, is to make something "similar" but I want to know how to "get" the document. How I can display the document or access it? One way to access document and manipulate the document. 

Thank you so much.