here is an example of mine for an introduction for two articles (so you can apply same format for three articles):
Recent controversy regarding the Australian educational system has prompted fiery debate as to whether a national curriculum for the entire nation should be implemented. Two opinion pieces offer contrasting views on the issue. In an article published in The Age on 28 March 2013, “Why should schooling change at every State border?” Stephen Buckle contends that a national curriculum must be introduced into all Australian schools. Conversely, an anonymous article published in The Herald Sun on 29 March 2013, “A SINGLE CURRICULUM IS NOT THE ANSWER”, argues that the national curriculum is necessary for the future of Australian education. An accompanying cartoon seems to endorse The Herald Sun’s view in its portrayal of the national curriculum as a robotic machine. The issue highlights the conflict between uniform education and society’s need for diversity in academic domains and beyond.
always, in the introduction, introduce each of the articles and the image and state their contention. however, i never wrote the tone/audience in the introduction and do not advise it (though many teachers do). tone and audience are part of analysis, so it would seem better to position them at the start of the first paragraph (you are not analysing in the introduction)!