A Literature Review is a summary of what scholars in your field currently know, understand, and accept as true about your topic, as well as the most recent developments in the field. Writing a literature review is not the same as adding sources to your research paper: a literature review should include the most relevant and important scholarly research being done on your topic.
Once you have your sources, you need to explain to your reader how the topic is currently understood and written about. Use these articles as examples or illustrations of what is currently known. Your paper will build on the knowledge and arguments made in the articles in your literature review, so it is important for you to acknowledge them, and to lay the intellectual foundation for your paper.
Great sources of articles, and freely available to the public!
These sources are more focused and less general.
Another place to look for journal articles online.