Introduction (2-3 pages)
Introduce the topic
Provide background on the topic to explain why it is important
Assert the thesis (your view of the issue). More on thesis statements can be found below.
Your introduction has a dual purpose: to indicate both the topic and your approach to it (your thesis statement), and to arouse your readers interest in what you have to say. One effective way of introducing a topic is to place it in context to supply a kind of backstory that will put it in perspective.
You should discuss the area into which your topic fits, and then gradually lead into your specific field of discussion (re: your thesis statement).