How does the internet help extremist reach their goals?

Your literature review should provide a broad overview of the research that is important to your study. This section of your thesis should begin with a few introductory paragraphs where you frame the research topic and its significance. To do this you will need to summarize all of the major relevant arguments on the research subject, highlighting the main issues and how the various schools of thought differ. If there are key terms to define the reader should do that here. This section should be organized thematically, so rather an discuss one source within a paragraph you would organize your paragraphs around themes or arguments within the literature. For example, if deterrence theory is important to your research (either it is the main theory in use, or parts of it are important to your research) you would discuss this concept using a variety of references that help demonstrate the scope of knowledge surrounding this theme. 
The sources you use within your paper matter greatly to the overall credibility of your research. For this reason a majority of your sources should be coming from peer-reviewed articles, scholarly texts, or other appropriate sources an websites.