An excellent start for locating journal and magazine articles is to use an index or bibliography. Columbia University Libraries subscribe to hundreds of journal indexes that are available online. There are several that concentrate on indexing all of the major publications in the area of film studies.
Link to the Film and Television Guide for a selected list. FIAF and Film and Television Literature Index are the best for completing a comprehensive search of the major journals in film studies. Depending on your topic, you may also search indexes that cover major disciplines such as American history, philosophy, religion, anthropology, etc.