A Levels may be the first time you have to write about historiography in a history essay, it was for me! However, it is not as daunting as it may first seem and I would recommend you practice a few historiography paragraphs before an exam to get used to the style. Depending on your course, you may have to write a historiographical essay, or include a paragraph about the historiography of the subject. One of the things that is different about historiography from a normal history essay is that you may have to be more critical than you would normally. Address individual historians or interpretations, and then say whether you think they are effective. Are they a true reflection of the time? There usually isn't a right answer to this, as it's very subjective. This is the beauty of a historiographical essay or paragraph. You can be creative and give your own opinion on the topic, perhaps more than you could in an ordinary essay. As an example, I will describe how I talked about a colonial historian. There are many explanations for colonialism and imperialism, and therefore it makes a very interesting historiographical essay. This particular essay was on Egypt. J.A Hobson argues it was a small elite of greedy capitalist investors that pushed intervention in Egypt, and later the occupation of the Suez Canal in the 50s. While this is certainly a solid argument for colonialism in general, it may not be so applicable to Egypt. Hobson's argument may be flawed as figures show that economic investment was insignificant in Egypt compared the settlement colonies. Here, you can cite some facts and figures. You might also want to mention something about the historian's background if relevant. Hobson was a socialist, and here his interpretation is obviously coloured by his political alignment. This may be a flaw for some students who believe in the objectivity of the historian. Although, what historian doesn't have his own biases? Either way, it can be worthwhile to pluck out some biographical or contextual information about the historian if you feel it is relevant. Sometimes these extra bits of research can be what pushes your answer from a B to an A.
It is this critical analysis of both the historian/interpretation of the argument backed up by historical knowledge that makes historiography useful in the essay. There is no point quoting a few historians and not exploring how they contribute, or fail to contribute, to our knowledge of the era or the argument you are giving. Therefore be careful not to just name drop, every point needs analysis and evidence, as you would have in a normal essay. The only difference is, you have a direct narrative to analyse and this can actually make giving evidence, or arguing there is no evidence, easier.