Historiography is basically the perspectives of historians, and to integrate these into History essays all that is need is for example is: J. Smith argued that "World War I was due to German Empirical Expansion". Generally you would include Historians in responses when there is quite a lot of controversy, or where a Historian presents an unique view on a subject, or sheds light on a debate or information.
It depends on the topic in which you are studying to where you can find historical documents. Usually your teacher will give students excerpts from Historian's publications, or just photocopies of textbooks which will say 'J.Smith said...' and it would be up to you to find their book to gain further Historiography. Basically, you won't find much online, as most will be in books and / or articles.