Merinda Hensley gave permision for content to be borrowed by permission from Literature Review: Demystified LibGuide from the University of Illnois at Urbana-Champaign.
Once you've decided what you want to write about you will need to conduct a systematic review of journal literature to establish what has been written in your field.
Databases enable you to combine search terms and locate high quality journal articles, conference papers and proceedings from a wide range of sources. Have a look at the Accessing Databases tab to choose the right one for your subject area. There are links to brief online tutorials or pdf guides to help you with using each of the databases there too.